The Big Bang Theory

The Plimpton Stimulation

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The Plimpton Stimulation
Big Bang Theory episode
Season 3, Episode 21
May 10, 2010
Guest star(s)
Episode guide

"The Spaghetti Catalyst"

"The Staircase Implementation"
Season guide

Season 2

Season 4

"The Plimpton Stimulation" is the twenty-first episode of the third season of the American sitcom The Big Bang Theory. This episode first aired on May 10, 2010.


Dr. Elizabeth Plimpton visits at Sheldon's invitation and she seems more interested in sleeping with everyone rather than visiting Caltech.

Extended PlotEdit

Dr. Plimpton in the flesh.
AskeuhdAdded by Askeuhd
Go for it Leonard.
Welcome to the Penthouse forum.
Dr. Elizabeth Plimpton, a cosmological physicist from Princeton University, comes to Caltech for a visit. At first she seems like a typical absent minded professor. Sheldon arranges her trip, and offers her to stay in his bed (with Sheldon sleeping on the sofa), rather than a hotel which he perceives as less hospitable. Leonard tries to impress her by talking to her about her work, but she's more interested in having sex with Leonard, which he very much welcomes. The next morning, Sheldon is completely oblivious to what happened overnight, but Penny immediately detects what happened based on Leonard's and Elizabeth's body language, and becomes jealous, because she broke up with Leonard not too long ago. Later that day, at the Caltech cafeteria, Dr. Plimpton meets Raj and wants to bed him, too. That night, Howard and Leonard come to Raj's apartment for Halo night and find Elizabeth there, so she suggests sex with all three guys. Howard and Leonard are uncomfortable at this since it would involve seeing each other naked. Leonard is also confused because he thought that he and Elizabeth shared something special. At last, Raj manages to lock the other two out and has sex with Elizabeth alone.  At the end of 

the show, Leonard and Penny discuss whether or not he needs to explain to Penny what happened. Although Penny keeps insisting that he doesn't need to explain anything, Leonard explains that he had sex with Dr. Plimpton because "she let him".


  • "You can't argue with good farce. Even in a short scene like the one we got at the end here it can generate tremendous easy laughter. Dr Plimpton tries to seduce Raj, Howard and Leonard at the same time leading to a really funny punch line...The problem was the writers couldn't decide who the story was really about. The first half of the episode was all about Sheldon as the writers exploited every amusing thing he could say about a female guest coming to stay. Then once Leonard slept with Dr Plimpton the episode became about him and how Penny would be affected by his dalliance...A fun episode with plenty to keep you chuckling. But wait for it...this could have been so much more." - The TV Critic's Review
  • IMDb user reviews


  • Title Reference: Dr. Elizabeth Plimpton comes to visit Sheldon for the purpose of science collaboration but winds up seducing the three other guys and having sex with Leonard and Raj.
  • Chuck Lorre's vanity card [1]
  • This episode was watched by 13.73 million people with a rating of 5.3 (adults 18-49).
  • This episode aired in Canada on May 10, 2010 with 2.3 million viewers and a weekly ranking of #8.


[The scene: Raj's apartment. Howard knocks at the door and Raj answers.]
Raj: [irritated] What?
Howard: What do you mean, "What?" It's Halo night.
Raj: I can't. I'm too sick. [coughs] Go away!
Howard: That's why we moved Halo night here. [holds up a paper bag] Look, I brought my mom's chicken soup.
Raj: I'm not hungry.
Elizabeth: [from inside the apartment] Don't send him away. Let him in.
Howard: Who’s that?
Raj: I bought a parrot.
Howard: Yeah, right. [goes in and sees Elizabeth on the couch] Dr. Plimpton?
Elizabeth: Hi. Howard, right?
Howard: Uh, yeah.
Elizabeth: Do you like role-playing games?
Howard: Yeah, sure. In fact, I'm a dungeon master.
Elizabeth: Not tonight. Tonight, you are a delivery man. You brought soup, but, uh-oh! Raj and I don't have enough money to pay you. So we'll have to come to some other kind of arrangement.
Howard: Beg your pardon?
Elizabeth: You two figure out the details. I'm going to change into something I don't mind getting ripped off my milky flesh. [She goes into the bedroom and closes the door behind her.]
Howard: What the frak?!
Raj: Go away! She wants New Delhi, not kosher deli. Besides, you have a girlfriend.
Howard: We broke up weeks ago.
Raj: Why didn't you say anything?
Howard: I was waiting for the right time. This is the right time.
[Leonard arrives.]
Leonard: Hey, who's ready for Halo?
Raj: Oh, this is like a nightmare. Get lost!
Howard: He's right. The numbers are shaky enough as it is.
Leonard: I don't understand.
Elizabeth: [opens the bedroom door slightly and peeks through] Oh, good. Leonard's here!
Raj: Good?!
Leonard: Elizabeth? What's going on?
Elizabeth: What's going on is you and Howard are my moving men and Raj is my new landlord and I don't have enough money to pay any of you! [She goes back inside the bedroom and closes the door.]
Leonard: Is she suggesting what I think she's suggesting?
Howard: Yep! Welcome to the Penthouse Forum.
Raj: Okay, show of hands. Who’s up for this? [Howard quickly raises his hand, but is the only one to do so.]
Leonard: We’ll all be naked in front of each other.
Howard: [quickly lowering his hand] I’m out.
[Elizabeth emerges from the bedroom wearing a bra and a very short skirt.]
Elizabeth: Everybody ready?
Raj: [whispering to Howard and Leonard] Follow my lead! [to Elizabeth] Almost. We’re, we’re going to go out into the hallway and, uh, make a dramatic entrance.
Elizabeth: Oh, good. It’s so much better when everyone commits! [She sits on the couch.]
Raj: Run. Run, run, run. Don’t look back.
[He hustles Howard and Leonard through the doorway. After they're out, he quickly closes and locks the door, then turns around and looks at Elizabeth.]
Raj: So. You say you can’t pay your rent?

[In Leonard's and Sheldon's building, Leonard happens on Penny in the lobby as she's on her way up from the laundry room.]
Penny: Oh, Leonard?
Leonard: Hey.
Penny: I found these in the dryer. [holds up a pair of Spider-Man briefs] I’m assuming they belong to Sheldon.
Leonard: Thanks. It’s really hard to find these in his size. [They start walking up the stairs.] So, listen. I’ve been meaning to talk to you about the other morning.
Penny: You mean, you and Dr. Slutbunny?
Leonard: Yeah, I wanted to explain.
Penny: Well, you don’t owe me an explanation.
Leonard: I don’t?
Penny: No, you don’t.
Leonard: So you’re not judging me?
Penny: Oh, I’m judging you nine ways to Sunday, but you don’t owe me an explanation.
Leonard: Nevertheless, I’d like to get one on the record so you can understand why I did what I did.
Penny: I’m listening.
Leonard: [after a long, long pause] She left me.

Elizabeth: Ah, Dr. Cooper, thank goodness. I completely forgot your address. But then I remembered that I’d written it on my hand. Lucky for me, I didn’t confuse it with what I’d written on my other hand, which are the coordinates for a newly discovered neutron star. ‘Cause if I tried to go there, I’d be crushed by hypergravity. Anyway, hello.

Penny: You know what? It’s, it’s none of my business. If you want to sleep with Sheldon’s doctor buddy right after we stopped seeing each other, go for it.
Leonard: Well, now…
Sheldon: Excuse me. I’m uncomfortable with you recommending that Leonard pursue having intercourse with Dr. Plimpton, who I assure you has better things to do.
Penny: I’m not recommending it. I’m saying it already happened.
Sheldon: That’s preposterous. Tell her, Leonard.
Leonard: Well…
Sheldon: No.
Leonard: Come on. It wasn’t my fault.
Sheldon: The implication being that you somehow tripped and fell into her lady parts?
Penny: You know what? I’m just gonna take the bus to work.
Leonard: Penny, I can still drive you.
Penny: Oh, no, no, it’s okay. You might slip on a banana peel and get me pregnant.



  • You make science come alive.
  • Leonard meets Dr. Elizabeth Plimpton.
  • Hi-lo.
  • Oh, it's Leonard.
  • I say it happened.
  • Sheldon, Elizabeth and Leonard.
  • So you say you have a problem paying your rent.
  • If you want to sleep with Sheldon's friend, I say go for it.
  • What the frak?
  • In the living room.
  • At the Caltech cafeteria.
  • And I don't have any money to pay you.
  • Elizabeth wrote down the street address on her hand.
  • Penny knows Leonard and Elizabeth slept together.
  • Chuck Lorre Productions, #286

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