Extended PlotRushing down snow covered hills, Amy and Penny are video skiing. Amy is winning because her center of gravity is very low; she is built like a pyramid. Leonard sprained his ankle playing. While Penny wants him to go to the hospital, Leonard refuses to go into the ER with another video game injury. Sheldon enters the living room and turns down a chance to play the game since he is on is way out to Texas. He is leaving immediately. Leonard inquires if someone is sick. It seems that Sheldon's sister Missy is about to have a baby. Penny brightens up and is happy for the new Uncle Sheldon. Sheldon tells everyone that he is going to be Uncle Dr. Cooper. Amy wonders why no-one knew that his sister was pregnant. Sheldon also didn't mentions his brother's kidney stones. He then asks everybody people want to know everything that was coming out of his family's genitals. Sheldon is going to fill in for his brother-in-law that was in a horrible motorcycle accident. Sheldon feels that he is lucky since he doesn't have to be there for the blessed event. His sister Missy is due the next day, but since it took her six years to get through high school, Sheldon doesn't know how long it's going to take. Amy offers to give him a ride to the airport, but he doesn't want to inconvenience his girlfriend. He does turn to Leonard and tells him that they have to leave in ten minutes.
Everybody minus Sheldon is together for a tree decorating Christmas party. Since Sheldon is absent, so are all of his tree decorating rules (including the required spacing of the ornaments.) Now, both Star Trek and Star Wars ornaments can now be on the same branches. The fact that Howard is enjoying trimming the Christmas tree might cause his mother to have a heart attack. Bernadette then takes the opportunity to photograph Howard trimming the tree. Penny is a little short of funds this year so her Christmas present is going to be giving him herself, which is what Leonard got last year and last night. Stuart then joins them as Amy's computer notifies her of an incoming video chat from Sheldon. He thinks that they are so thoughtful that they have a Christmas party after he left since he isn't into Christmas. His sister has been in labor for an hour and is having a home birth. Raj points out that many women want to give birth at home in a warm comfortable environment. Sheldon feels that she will also turn her bedroom into an "amniotic Slip and Slide." Sheldon then gets called away to have a family picture taken because his sister is fully dilated and there is no blood yet.
Raj wants to know if Amy would want Sheldon there if she was having a baby. Penny breaks in that she doesn't think Sheldon will be there when they make the baby. Bernadette brought over the holiday film "It's a Wonderful Life," to watch. Neither Raj nor Stuart has seen it. Amy describes the movie as being at Christmastime, Jimmy Stewart is really depressed and wants to jump off a bridge and kill himself which is pretty much Stuart's life story. Bernadette then adds that he gets to see what life would be like if he never was born. Penny wonders if anyone ever considered life without someone. (Leonard: "Knock... knock... knock... What do you think?... Knock... knock... knock... What do you think?... knock... knock... knock... What do you think?" doing Sheldon's knock.) Amy points out that despite the jokes they make about Sheldon, none of them would be there if it wasn't for Sheldon. None of them would know Amy. Bernadette would never have met Howard. Leonard would not have been dating Penny. Leonard disagrees because he has been going to The Cheesecake Factory for years and he could have still picked her up causing everybody to laugh. Penny then explains what would have happened.
Howard, Raj and Leonard are having a meal and Leonard tells them that he is going to finally ask her out. Penny comes over to ask what they want to eat and Leonard can't even speak to her. He then walks over to her, introduces himself and tells her that there is something he has wanted to ask her for a long time. If she is not too busy he wants to know if she could tell him...where the restroom is. Penny remarks that he is too late looking strangely at him.
Back in Apartment 4A, Leonard objects that he would not have wet himself though Raj and Howard think that she got the story right. Leonard did ask Penny out, but that could not have happened if he hadn't moved in with Sheldon. Of course, Penny would never have introduced Howard to Bernadette. Howard replies that he could have also met her when she was a waitress.
Bernadette explains her version where she tells Penny that she finds Howard cute. Then she sees Raj feeding Howard a bite of his dessert and then cleaning off his mouth with a napkin and Bernadette changes her mind. Leonard then confronts Penny that she wouldn't have done so great herself due to the type of guys she had been dating.
In Penny's apartment she is preparing food and in walks Zack Johnson who calls her babe. She asks if he paid the rent and instead Zack bought some magic beans. Then Leonard makes them both pee on themselves since Penny did the same thing to him.
Sheldon calls back claiming that he has seen lady things that he "shouldn't have seen." According to Amy, they don't normally look like that. Sheldon then says that that is people should not be coming out of people to make new humans; to him, it's like a "dirty magic show." Sheldon's mother calls him to bring a mop. Sheldon is distraught that despite having two PhDs, he is reduced to being the janitor of his sister's birth canal.
Sheldon sends everyone a holiday email including a picture from the birthing room that disgusts Leonard, Penny, and Raj. Back to the "It's a Wonderful Life" discussion, Penny would still have met Sheldon. Amy describes how without Leonard there, Penny would try and seduce Sheldon.
Penny stalks Sheldon in the laundry room wearing her short shorts. She saunters over to him and asks if he is doing his laundry. Of course, because Saturday night is laundry night and he is in a laundry room. Sheldon tells her that her inference is justified which Penny thinks is so funny. Penny is going to do her dirty laundry, which isn't as dirty as the dirty girl wearing them, who starts to undress. The real Penny wants her to stop, but the guys disagree. Now in her bra, Penny asks Sheldon what he thinks. He finds her a tad asymmetrical, but nothing to worry about. Penny tells him that they are going to do it in the laundry room right now. Sheldon reminds her that he is saving himself for a bespectacled neurobiologist who has hair the color of mud as Amy tells the story.
Sheldon calls back from Texas saying that things are going better. His mother asked him to get some towels, so he left and went to "Bed, Bath and Beyond". Missy then screams while Sheldon is on the phone which he finds very rude. Amy has now diagrammed the absent Sheldon premise and tells Penny that she would never have met comic book legend Stan Lee. Howard would have always known Raj and Leonard. Leonard never got an apartment with Howard because of the latter's "serious relationship with his mother". Bernadette again mentions that if they had not met, he would still be living with his mother.
Howard tells his version, first he is taking his mother her lunch in her bedroom and that she didn't get enough food. Later he is seen feeding her, but she is still in the bedroom dead reminiscent of the mother in the movie Psycho with Howard now doing her voice. Howard is neutral on whether she starved to death or if he actually killed her.
Leonard and Raj did not move in together because Raj thought he was going to be a ladies' man.
In Raj's scenario, Leonard is living with him as Raj cooks dinner for a fat Leonard. Since he had no girlfriend, he compensated by overeating, so Raj deep fried some food. Then Leonard also makes Raj fat in the living together scenario. Then Stuart shows up (fat) to have dinner with them because he wants to be in someone's story.
In Amy's case, without Sheldon she is alone in her apartment crying over a cupcake and singing "Happy Birthday" to herself. (Happy Birthday to me, Happy Birthday to me. There's tears in the frosting, Happy Birthday to me) Stuart shows up and blows a party favor in her face to be in another story.
Sheldon is back reports that his sister had a baby boy. Sheldon was not sure he was going to make it, however his mother gave him some ice chips and his sister (in labor) kept giving him encouragement. He's not going to go back because he finds the baby irritating since he has literally been crying his entire life. Howard tells him that the baby is already taking after Uncle Shelly. Amy tells him to return to be an intelligent role model for his nephew, to which Sheldon agrees. They were amazed that Sheldon did exactly what Amy asked him to do. Even though Amy kept telling the gang the impact Sheldon had on them, he has had an impact on Amy too. Amy felt if that were really true she wouldn't still be living alone. Leonard tells her that Sheldon cares for her more than she really thinks. Amy doesn't believe him so he shows that her picture is on Sheldon's screen saver along with Swamp Thing, Madame Curie, Stephen Hawking, etc. Amy gets excited that Sheldon is really into her. And she doesn't mind Madame Curie being there because she is already dead.
After Sheldon returns, Amy is walking up the stairs and staring at Sheldon. She tells Sheldon that she missed him to which he quotes Han Solo, "I know." After Amy asks if he missed her, he replies that he would have liked her to be with him (or had gone in his place). Amy also wonders how he felt holding his nephew hoping that he might want one with her someday. He looked into the blank innocent eyes of someone who didn't comprehend anything he said, which he said was like another day at the office for him.
Finally, a fat Raj and Leonard are eating at the Cheesecake factory and again Leonard asks Penny out. She already has a boyfriend, a very suave looking Stuart. Of course, this situation was Stuart's Christmas fantasy.
This episode shows a number of "What if?" scenarios imagined by members of the group. There is not a lot of logic to what led to these universes, but the primary idea behind the imaginations is having someone removed from one person's life or more.
Sheldon wasn't a member of the group
In this universe, Sheldon was presumably never born or never came to live in the exact apartment. However, Leonard still lived in the apartment building, suggesting he still lived across the hall (with a different roommate) or lived in a different apartment. Most of the scenarios emerge from this idea and might form one single alternate universe.
Leonard doesn't date Penny (narrated by Penny)
In the first scenario, Leonard still had a crush on Penny and wanted to ask her out; however, Sheldon's accidental influence had prevented him from even accidentally asking her out, meaning he never slowly worked up the confidence to ask her out in the first place. Penny images what would have happened if Leonard tried to ask her out.
At the Cheesecake Factory, Leonard, Howard and Raj are about to place their order to Penny. Leonard tries to ask her out while she is standing at the table, but only utters a bit. He gets up and tries again, but ends up so nervous he pees his pants. Leonard, interrupting the imagination, says that is not what would have happened.
Bernadette doesn't date Howard (narrated by Bernadette)
In the second scenario, due to Penny and Leonard not dating, Howard and Bernadette's first date doesn't take place. While at first finding Howard cute, she changes her mind when she sees how close he and Raj are, which creeps her out.
Penny lives with Zack (narrated by Leonard)
In this variation of reality, Penny is living with Zack. Zack is shown to be potentially more stupid than in the real universe, as instead of paying for rent he buys "magic" beans. Just for the fun of it, he also adds that both Zack and Penny ended up peeing their respective pair of pants.
Leonard never lived with Sheldon (narrated by Amy)
In this imagination, Leonard either never existed, never moved into the apartment or moved out of the apartment but Sheldon still lived across the hall from Penny. These scenarios stand apart from the ones where Sheldon was omitted. Amy comes up with a story about Penny being attracted to Sheldon and trying to advance to Sheldon in the laundry room. However, he responds to her advances by saying he wants to save himself for someone fitting Amy's description. Amy doesn't specify whose Sheldon's roommate is in her story, as Sheldon would still have been looking for one.
Howard's "Psycho" Reality (narrated by Howard)
In this universe, Mrs Wolowitz has been dead for some time. In his shock, Howard has gone insane and pretends she is still alive, mimicking how she speaks to have "conversations" with her. It is unknown how she died, as the real Howard leaves it up to speculation whether he killed her or she simply died from an unknown cause. Howard based this story from an exaggeration of his rather small dislike for his mother.
Leonard is overweight (narrated by Raj)
This story describes Leonard and Raj having agreed to move in together as roommates. As a result of having no girlfriend, Leonard tries to stop his depression with food. This leads to him gaining a ridiculous amount of weight. This story can fit in the one where Sheldon doesn't exist and also the one where Penny is attracted to Sheldon.
Only Leonard is overweight
Raj's original story has only Leonard fat, while Raj happily makes him lots of food. Leonard interrupts the story and suggests Raj is fat too. Raj alters the story.
Leonard and Raj are both overweight
Leonbard & Raj are at the dining table, having finished a ridiculously big dinner. The story is suddenly interruped by a fat Stuart entering. Stuart says he wanted to be in someone's story too.
Amy never met Sheldon (narrated by Amy)
In this universe, due to Sheldon presumably not existing, meeting Leonard, Leonard meeting Howard and Raj, or the circumstances for her and Sheldon's meeting not happening, Amy is alone and miserable on her birthday. She is crying while singing happy birthday to herself while holding a small cupcake. While not confirmed, it is possible this universe exists in the universe above, due to Sheldon not being part of the group in it. The imagination, however, is altered by Stuart again taking over the story to include himself.
Penny is dating Stuart (final scene, not narrated)
The final scene is a combination of several concepts of the other stories told. Leonard again fails to ask out Penny, again he is fat, again Raj is too. Again Stuart plays a random part in it, dating Penny. It looks like an idealized version of Stuart, much cooler and smooth than the regular Stuart, and potentially richer.
- Guest starring:
- Teleplay: Jim Reynolds, Steve Holland & Tara Hernandez
- Story: Steven Molaro, Eric Kaplan & Maria Ferrari
- Jesse Schedeen for IGN - Without Sheldon, the Big Bang Theory probably wouldn't have been very successful. And that idea was sort of at the heart of this week's holiday-themed episode. Taking a little inspiration from It's a Wonderful Life, the rest of the gang wondered how their lives might have played out if Sheldon weren't around. Would they still big a tight-knit unit?...But again, what we were given was entertaining enough. It was amusing to see the course each character's life took without Sheldon as a guiding influence...This was a perfectly decent holiday episode to cap off 2013. It offered fun glimpses of a world without Sheldon Cooper (as well as one where Penny had the hots for Sheldon), and it gave Amy the happy ending she deserved. 
- Dhruv Rao of The DR Club gave this episode a B. 
- IMDb user reviews
- Title Reference: The members of the gang consider how their lives would be different if Sheldon is taken out of the picture.
- Taping date:
- Chuck Lorre's vanity card. 
- This episode was watched by 17.68 million people with a rating of 5.1 (adults 18-49).
- Total viewers including DVR users 23.44 million.
- The Big Bang Theory was ranked #3 for the week ending December 15, 2013.
- This episode aired in Canada on December 12, 2013 with 4.072 million viewers with a weekly ranking of #1.
- In the United Kingdom, this episode aired on April 10, 2014 with 1.88 million viewers and a weekly ranking of #1.
- In Australia, this episode aired on February 25, 2014 with 1.17 million viewers.
- Episode transcript 
- Sheldon wears an unknown light blue shirt featuring a robot and in Amy's imagination, his Green Lantern logo on green shirt (in the laundry room with Penny) and his green "Prehistoric Monsters" (aka dinosaurs) on black t-shirt
- Leonard wears his festive red periodic table t-shirt
- First time that in a video game, all the players are female characters (Penny and Amy). They are playing skiing game in Kinect Sports: Season 2 on the Limited Edition Kinect Star Wars Bundle of XBox 360 that previously appears in The Extract Obliteration (S6E06) and The Contractual Obligation Implementation (S6E18).
- First appearance of Mrs. Wolowitz's bedroom.
- This episode was filmed on two separate days, and the audience included people who were touring WB Studios like "The Scavenger Vortex" (S7E3) which had many short scenes in it.
- The scene that Howard turns his mother around to reveal that she is dead and a skeleton (in Howard's imagination) is an obvious reference to Alfred Hitchcock's classic thriller Psycho.
- First episode since "The Engagement Reaction" (S4E23) in which Bernadette is shown working at the Cheesecake Factory, although this scene was only her imagination.
- Sheldon or Amy don't appear to sit on the empty chair with Raj, Howard and Leonard in the first fantasy Cheesecake Factory scene of this episode and Bernadette is not seen as the Cheesecake Factory waitress with Penny that time as she might be on a different shift during that fantasy Cheesecake Factory scene.
- Leonard and one of the members of the 'Shamy' duo (either Sheldon or Amy) are not there on these two empty chairs at the table where Howard and Raj are sitting at in the second fantasy Cheesecake Factory scene of both Bernadette and Penny as Cheesecake Factory waitresses.
- As of that sequence Amy did not see both Penny and Bernadette work as Cheesecake Factory waitresses together since five episodes in Season 4 with Cheesecake Factory scenes (S4E3, S4E4, S4E13, S4E16 and S4E23) whereas she only saw Bernadette and Penny do a separate job each (Bernadette: waitress, Penny: barmaid) at the Cheesecake factory instead of both of them being Cheesecake Factory waitresses in "The 21-Second Excitation" (S4E8).
- In Leonard's imagination about what if Penny ended up with Zack, instead of paying rents, Zack use the money to buy magic beans. This scene might be a humorous reference to "The Precious Fragmentation" (S3E17), in which instead of buying lunch, the gang bought a box of stuff from the garage sale, to which Penny mocked "you didn't trade the food for magic beans, did you?"
- The Sheldon-Penny scene is a tip of the hat to the Shenny [Sheldon and Penny should be together] fans, despite it is only a scene out of Amy's imagination.
- Penny offered to Sheldon to have sex in the laundry room with her, though she wouldn't do it with Leonard in "The Stag Convergence" (S5E22). This scene was also only a fantasy of Amy's.
- Sheldon doesn't mention that in the last episode Missy appeared in, he spoke of her offspring being potentially another Sheldon-like genius since they have the same DNA heritage. Here she has her first baby.
- The audience again gets to see Mrs. Wolowitz, or at least her body.
- While Howard walks into Mrs. Wolowitz's room, on the wall to the right, the wedding picture of Howard and Bernadette with the gang is clearly visible. It would be better if it had a picture of Ms. Wolowitz like in the episode "The Engagement Reaction" (S3E23) as they are talking about Howard going out with Bernadette because of Sheldon.
- Mary Cooper returns after being absent from season 6, although we only hear her voice.
- Raj sat in Sheldon's spot for much of the episode while Sheldon was out of town.
- Second episode where Sheldon expresses dissatisfaction of menial work in regards to his talents. The first was "The Vacation Solution" (S5E16).
- Final time the Cheesecake Factory set is seen.
- First time TBBT has had a "what-if", "alternate reality" (AR) or "alternate universe (AU)" episode.
- Amy: (Skiing) Well, I have an extremely low center of gravity; I’m like a pyramid.
- Raj: So Star Wars and Star Trek characters can go on the same branch?
- Leonard: I know, it’s crazy. Welcome to the Thunderdome, people.
- Howard: I've never done this before. It’s kind of fun.
- Raj: If your Mom could see her little Bar mitzvah boy right now, she’d have a heart attack.
- Bernadette: Good idea. I’ll take a picture.
- Sheldon: The second I go out of town, you throw a Christmas party without me?
- Amy: Yeah, kinda.
- Sheldon: That’s so thoughtful. You guys are the best.
- Sheldon: She chose to have a home birth because she wants to live in the stone age and a cave wasn't available.
- Raj: You know, many people believe that home births are better because the mothers are in a warm environment where they can be nurtured by love ones.
- Sheldon: And turn the bedroom floor into an amniotic Slip n’ Slide.
- Leonard: You know, maybe you and I wouldn't be together, but you wouldn't have done so great yourself.
- Penny: Why?
- Leonard: Because I know exactly the kind of guy you would have ended up with.
- Zack: Hey, babe.
- Penny: Hey, did you remember to pay the rent?
- Zack: Better. I used the money to buy these magic beans.
- Bernadette: You know, I was thinking. Without Sheldon, most of us would have never met, but Penny would have still lived across from him.
- Amy: And with Leonard out of the picture, we all know what that would mean.
- Penny: We do?
- Penny: Hey, Sheldon. [Fantasy Penny enters laundry as Sheldon sorts his.]
- Sheldon: Hello.
- Penny: Doing laundry?
- Sheldon: Of course I’m doing laundry. Saturday night is laundry night and I’m in a laundry room, so… I believe your inference is justified.
- Penny: Oh, my inference is justified. Sheldon, you are so funny, Anyway, I need to do my laundry, too, because these clothes are so dirty. Almost as dirty as the dirty girl who is wearing them.
- Penny: [Listening to the story.] OK, that’s enough.
- Guys: Disagree.
- Penny: So what do you think?
- Sheldon: A tad asymmetrical, but nothing to be concerned about.
- Penny: Please, Sheldon, I need you.
- Sheldon: To what?
- Penny: To take me.
- Sheldon: I’m not taking you anywhere till you put on a shirt.
- Penny: Come on, Sheldon. You and me right here.
- Sheldon: Penny, for the thousandth time, I’m saving myself for someone special. Perhaps a cute bespectacled neuroscientist with hair the color of mud.
- Penny: I think I know how to change your mind.
- Guys: That’s enough.
- Stuart: I was okay with it.
- Amy: Happy birthday to me. Happy birthday to me. There’s tears in the frosting. Happy birthday to me.
- Amy: Did you hold the baby?
- Sheldon: I did.
- Amy: And …how did it make you feel?
- Sheldon: Looking into the blank innocent eyes of a creature who couldn't begin to comprehend anything I was saying? Basically another day at the office.
- Amy: I missed you.
- Sheldon: To quote Han Solo – I know.
- Amy: Did you miss me?
- Sheldon: I would've preferred to have you there with me. Or instead of me.
- Mary Cooper: Sheldon Lee Cooper, you get back in this room right now! And bring a mop!
- Sheldon: Did you hear that? A mop. I've two PhD's, yet somehow, I’m the janitor of my sister’s birth canal.
- Zack: Oh, babe, I peed myself.
- Penny: Oh! Me too!
- Amy: You make jokes about Sheldon, but if It weren't for him I don’t think any of us would be sitting in this room right now.
- Howard: Really? Sheldon not being here is the main reason I’m in this room.
- Amy: It’s true. None of you would know me. You wouldn't know Bernadette. You wouldn't be dating Penny.
- Leonard: You don’t know that. I've been going to the Cheesecake Factory for years. I could have picked her up.
- Penny: [Everybody laughs.] Oh, you weren't joking.
- Leonard: No.
- Penny: OK, sweetie. Let me tell exactly how that would have gone down.
- Leonard: [Penny’s fantasy story.] I’m going to do it. I’m going to ask her out.
- Howard: I’m going to squirt chocolate milk out of my nipples. Sorry. I thought we were saying things that are never going to happen.
- Raj: Maybe this time he’s going to do it.
- Howard: Hope you’re thirsty. Here it comes!
- Leonard: Watch me.
- Penny: Hi. You guys ready to order or do you need a few minutes?
- Leonard: I..I..um.
- Penny: A few minutes it is.
- Raj: Hey, you knocked her out, but that was a lot of sound.
- Leonard: You guys are making me nervous.
- Howard: Fine. Go talk to her on your own.
- Leonard: I will. Excuse me.
- Penny: Yep.
- Leonard: Hi, um, I’m Leonard.
- Penny: Really? You don’t sound so sure.
- Leonard: No, I am he. And anyway there is something I wanted to ask you for a long time. Um.
- Penny: What’s that?
- Leonard: Well, I was wondering if you’re not too busy..um..if you’d be interested in telling me where the restroom is?
- Penny: I think you’re too late.
- Leonard: [Back in 4A.] Come on. I would have not peed my pants.
Gallery including Alternate Reality (AR) photos.
-  Taping Report by MJistheBOMB