Penny's promiscuous friend Christy from Nebraska is in town, and is easily picked up by Howard. They take over Penny's apartment, so she sleeps over at Sheldon and Leonard's apartment. Howard's affair takes up all of his time, leaving no space for his normal activities with the gang. Sheldon is distraught at the empty void in the team caused by his departure.
Howard shows Leonard and Raj the new voice recognition technology on his phone which turns out to be severely flawed. As the gang has wasted several minutes of their game time, Sheldon pesters them to commence Halo Night, but is interrupted by Penny, who then starts talking about her uninvited old friend from Nebraska; Christy. She accidentally mentions Christy's promiscuity, which quickly alerts Howard. While Penny is explaining Christy's history, they discover that Howard has disappeared and has been hitting on Christy in Penny's apartment. Surprisingly, Howard succeeds in seducing her and gets busy with her, leaving the gang short of one Halo player.
As Sheldon detests playing one-on-one, Penny has to replace Howard. Penny turns out to be naturally gifted at playing Halo, which angers Sheldon as he believes she is cheating. Penny, having had a fun night, retreats to her apartment only to come back moments later because Howard and Christy are using her bedroom for sexual intercourse. As a result, Penny sleeps in Leonard and Sheldon's apartment (though when they turn out the lights and head off to bed, they forget Raj is still in the kitchen, forcing him to sneak out and scaring Penny into following Sheldon's makeshift bed instructions). The following morning, Sheldon takes issue with Penny interrupting his Saturday routine of watching Doctor Who, when suddenly Howard makes a dramatic entrance and says "Hola, Nerdmigos". Penny wakes up and has found out that the amorous couple have befouled her robe, her loofah mitt and her stuffed bear collection. Christy then makes a grand entrance, and meets Sheldon and Leonard after kissing Howard. Penny asks Christy where she will stay, Howard offers Christy to stay at his mother's house. As Christy leaves, Penny warns Howard that Christy will sleep with him only as long as he keeps buying her things, but Howard simply responds "Really? Yea!"
Later, as Leonard, Sheldon and Raj are in a Chinese restaurant, Sheldon realizes Howard's importance in maintaining the integrity of the group. This point is reinstated when the gang asks Penny to play with them on Halo Night, but she refuses as she has plans to go dancing. As a result, Sheldon and the gang march over to Howard's house to confront him. But before they are able to confront him, they overhear Howard's mother and Christy having a big argument, which drives Howard out of the house. The argument leads to Christy breaking up with Howard, allowing him to return for Halo Night. While the gang is playing, Penny and her friends, knowing the guys are too engrossed in the game to notice them, have a laugh by telling the gang they want to have sex with them, and leave after the guys don't notice. Leonard does look up wondering what just happened and then goes back to his gaming.
- Guest starring:
- Teleplay: Lee Aronsohn & Jennifer Glickman
- Story: Chuck Lorre & Bill Prady
- "There is something missing from this episode. The story lacks a real punch and the jokes are solid but not spectacular. It is a credit to the show though that it feels close to something really good here rather than feeling like a disappointment." - The TV Critic's Review
- IMDb user reviews.
- Title Reference: When the gang orders Chinese, their order of dumpling appetizer comes with four dumplings which is non-divisible by the three of them.
- Chuck Lorre's vanity card 
- This episode was watched by 9.68 million people with a rating of 3.7 (adults 18-49).
- Episode transcript .
Sheldon wears the Kablaam Computer shirt (available from The CBS Store now that the original manufacturer, Blank Generation, appears to be out of business), another discontinued striped shirt from Urban Outfitters, and a Green Lantern logo shirt; Green Lantern being one of Sheldon's most frequent shirt choices, second only to The Flash.
Leonard's shirts in this episode include: a Rubiks Cube shirt titled "Twisted" , a white "Recycling" logo shirt , and his American Phytopathology Society shirt (they make their "member" shirts available to the general public, so please support them with your purchase).
Howard wears a red and white checkered belt, with a rhinestone Flash buckle.
Christy's only known outfit consists of Lucky Brand Blue Flower Shorts, and a Culture Phit Cami Corset With Lace in green.
Penny wears a Truly Madly Deeply Rainbow Hoodie, which is sadly discontinued.
For dancing, Penny wears a printed halter dress by Guess.
Several items appear for the first time in this episode:
- Periodic table magnet on the fridge.
- Docking station on the end table next to Sheldon's spot. Later this tablet will move and most often be seen on the trunk next to the refrigerator.
- Halo 3 Master Chief's helmet on the table at the edge of the alcove.
- This is the first appearance of the voice of Mrs. Wolowitz.
- Leonard's surname Hofstadter is revealed for the first time in this episode.
- At Szechuan Palace, Sheldon explains that the gang's standard order includes the steamed dumpling appetizer, consisting of four dumplings to be divided among the four of them. Later, in "The Dead Hooker Juxtaposition" (S2E19), Sheldon is horrified when his dumplings are steamed, exclaiming that "...you hear stories of this sort of thing, but you never think it'll happen to you".
- Leonard tells Sheldon in "The Irish Pub Formulation" (S4E6) that Raj once used Sheldon's toothbrush, and Penny later admits to using Sheldon's toothbrush in "The Anxiety Optimization" (S8E13)
- When Sheldon is watching "Doctor Who", The Doctor's sonic screwdriver can be heard, making it likely that the episode was "The Sound of the Drums" or "Last of the Time Lords".
- Sheldon states that if he could afford the rent he'd ask Leonard to leave. In "The Financial Permeability" (S2E14), Sheldon states that his expenses account for 46.9% of his after tax income. As expenses must include his rent, clearly he can afford the rent on his own assuming a roughly 50/50 agreement with Leonard.
- First episode where Penny's brother is mentioned.
- Christy, unfortunately, doesn't meet Raj.
- There are several inaccuracies in this episode regarding Halo:
- In the real game of Halo 3, you can't actually shoot off someone's head, but it's possible that Penny might be exaggerating what she actually did.
- In Halo 3, there are no med packs.
- Howard says to shoot the person that's charging their plasma rifle, but a plasma rifle only shoots repeated shots of plasma. A plasma pistol has the ability to charge a shot.
- Sheldon says, "Okay, assuming we could dance, which we can’t, there are three of us and two of them," which is contrary to his statements in "The Agreement Dissection" (S4E21), "No, thank you, but for the record, I’m an excellent dancer, proficient in the rumba, waltz and cha-cha. ... In the South, pre-adolescent children are forced through a process called cotillion, which indoctrinates them with all the social graces and dance skills needed to function in 18th century Vienna."
- Sheldon suggests to Penny that she sleep not facing the door so as to protect herself against marauders. In "The Hamburger Postulate" (S1E5), however, when he sleeps on the couch, he does so with his head to the door.
- Sheldon states that he would watch the "last 24 minutes of Doctor Who. Although at this point it's more like Dr. Why Bother?" The current Doctor Who series has episodes 45 minutes long. He did not stand there talking for 21 minutes, and it's highly unlikely that he came in 15-20 minutes late. He would've missed most of the episode.
- Sheldon claims that he has watched Doctor Who" every Saturday since I have lived in this apartment." The present run of Doctor Who began in March 2005, at least two years after he moved into the apartment (assuming he started living in the apartment in 2003, which would correspond to his statements in "The Luminous Fish Effect" (S1E4) and "The Staircase Implementation" (S3E23)). It is possible, though, that given the level of computer skills available to the gang, he could have hacked into the British Broadcasting Corporation's "BBC iplayer" service, which allows catch-up via the Internet for the most popular shows. This is meant for domestic consumption only and is not normally accessible from outside Britain, but do little details like this deter Sheldon and the gang?
- Sheldon also claims he has also always sat on his spot on the couch, but as revealed in "The Staircase Implementation", the couch was not present when Leonard first moved in.
- The morning after "Halo night" is revealed to be a Saturday, due to Sheldon's expression regarding his watching of Dr. Who, but at the end of the episode when the guys ask Penny to play Halo with them Halo Night is said to be Wednesday night, not Friday night.
- Penny tells Howard to keep her robe, however she is seen wearing it in future episodes, although it is possible she bought a new one.
- Howard's voice recognition on his phone is a precursor to the Siri app on the iPhone, which is actually used in a later episode.
- Raj has selective mutism rendering him unable to talk in front of women; however, in one scene Sheldon complains that they always play Halo in teams, Leonard says that the only way they can play teams is if they cut Raj in half, to which Raj replies: "Oh sure, cut the foreigner in half, there's a billion more where he came from!". Penny is standing there for the whole of this scene and offers to be the fourth player. It's possible Raj has consumed alcohol which would suppress his selective mutism, however he hasn't discovered this until the following episode "The Grasshopper Experiment" (S1E8). Also, there are no visible alcoholic containers (such as bottles) on the table to make the connection that Raj has had anything to drink.
- Raj may not have noticed this as his selective mutism stems mostly towards talking TO women.
- (The guys are at Leonard and Sheldon's place for Halo night. While Sheldon is setting up the Xbox 360 to the T.V., Leonard, Howard and Raj are trying the new voice search on Howard's phone.)
- Howard: Watch this, it's really cool. (To phone) Call Leonard Hofstadter.
- Phone: Did you say: Call Helen Boxleitner?
- Howard: No, c- call Leon-nard Hof-stad-ter!
- Phone: Did you say: Call Temple Beth Sader?
- Howard: No.
- Leonard: Hey, here, let me try. (To the phone) Call McFloono McFlooneyloo (chuckles).
- Phone: Calling Rajesh Koothrappali.
- (Raj looks up in confusion and shock, then his phone rings.)
- Raj: Oh, ho, ho, very impressive! And a little racist.
- (Penny, Sheldon, Leonard, and Raj are playing Halo at Leonard and Sheldon's apartment)
- Sheldon: OK, that's it! I don't know how but she's cheating. No one can be that attractive and this skilled at a video game. (Sheldon walks away furiously)
- Penny: Wait, wait Sheldon, come back you forgot something.
- Sheldon: What?
- Penny: This plasma grenade! (throws a plasma grenade at this character, and laughs with Leonard, while Raj is surprised) Look, it's raining you! (laughs on)
- (Sheldon, Leonard & Raj go to convince Howard to join them for Halo Night).
- Leonard: Sheldon, think this through. You're going to ask Howard to choose between sex & Halo.
- Sheldon: No, I'm going to ask him to choose between sex & Halo 3. As far as I know, sex has not been upgraded to include high def graphics & enhanced weapon systems.
- Leonard: (sarcastically) You're right. All sex has is nudity, orgasms, and human contact.
- Sheldon: My point.
- Christy: (From inside the house) I'm just saying you could take your damn plastic off your couch once in a while!
- Mrs. Wolowitz: WHY?! SO YOU AND HOWARD CAN GO HUMP ON IT?!
- Howard: (tries to stop Christy and Mrs. Wolowitz' yelling) Ladies, ladies, I'm sure there's a middle ground.
- Christy and Mrs. Wolowitz: SHUT UP, HOWARD!
- Howard: You girls talk, I'm gonna take my scooter out for a little spin.
- (Howard leaves and finds the guys on the front porch.)
- Christy: Oh, you happy?! You drove your son out of your house!
- Mrs. Wolowitz: WHY DON'T YOU STOP BUTTING IN WHERE YOU DON'T BELONG?!
- Howard: (comes outside) Hey, what are you guys doing in here?
- Christy: And why don't you start treating him like/as a man, then?!
- Sheldon: I-It's Halo Night.
- Mrs. Wolowitz: HE'S NOT A MAN, HE'S A PUTZ, AND DON'TCHA TAKE THAT TONE WITH ME, YOU GOLD DIGGER!
- Christy: What did you call me?!
- Mrs. Wolowitz: YOU HEARD ME! AND I'LL TELL YOU SOMETHING ELSE: YOU'RE BARKING UP THE WRONG TREE, 'CAUSE AS LONG AS YOU'RE AROUND, HOWARD'S OUTTA THE WILL!
- Christy: You know what, I've got better offers, I'm outta here!
- Mrs. Wolowitz: THAT'S RIGHT, (bangs on the door with a crash.) GO BACK TO BABYLON, YOU WHORE (WHOAH)!
- (There's an awkward pause between the guys)
- Howard: So, Halo Night, huh?
- (They start to leave)
- Raj: I thought she was the whore of Omaha.
- Sheldon: Shh!
- (The guys are playing Halo 3, and the atmosphere is intense)
- Howard: Sheldon, you got him in your sights! Fire, he's charging his plasma rifle!
- Sheldon: I can't shoot now, I'm cloaking!
- Leonard: Raj, kill Sheldon!
- Raj: I can't see him!
- Sheldon: That's why they call it cloaking, dead man!
- Leonard: Well, just start throwing grenades!
- Raj: I'm all out!
- (Penny and her three friends enter the apartment)
- Penny: Hey guys, my friends and I got tired of dancing, so we came over to have sex with you.
- (The guys are too engrossed in their game to even notice the girls are present)
- Leonard: Raj, now jump in the tank!
- Sheldon: We said no tanks!
- Raj: There are no rules in hell!
- Howard: MED PACK! I NEED A MED PACK!
- (Penny turns to her friends)
- Penny: Told ya!
- (They leave, laughing)
- Leonard: (on his feet now) There's a sniper, use your rocket launcher!
- Raj: All I've got is a needler, and I'm all out of ammo!
- Sheldon: And now you're out of life!
- (As he's about to kill Raj, Leonard suddenly pauses)
- Sheldon: Why'd you hit pause?
- Leonard: I thought I... heard... something.
- Raj: What?
- Leonard: Oh, er, never mind, sorry!
- (They resume playing)