321 - The Plimpton Stimulation
Aired May 10, 2010

The Plimpton Stimulation

The gang is surprised to hear Sheldon is having a female guest stay over. Although Sheldon's interest in his guest is purely academic, Dr. Elizabeth Plimpton invites a different kind of attention when she meets Leonard, Howard and Raj.

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Guest Stars: Judy Greer as Dr. Elizabeth Plimpton

Writers: Chuck Lorre (Story), Bill Prady (Story), Lee Aronsohn (Story), Steven Molaro (Teleplay), Jim Reynolds (Teleplay), Maria Ferrari (Teleplay)

Director: Mark Cendrowski

Viewers: 13.73 million Households Rating: 8.2/13 Adults 18-49 Rating: 5.3/13

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Episode Notes

  • The title refers to Sheldon's guest, Dr. Elizabeth Plimpton, and the stimulating effect she has on the guys.

> Bazinga

When the guys are surprised to hear Sheldon will be having a female companion stay in his bedroom, they wonder whether he's kiding them. Sheldon tells Howard "A, I rarely kid. And B, when I do kid, you will know it by my use of the word Bazinga". When Howard asks if the two of them will be sleeping in the same bed, Sheldon tells him "Yes. Bazinga."

> Roommate Agreement

When Leonard wonders whether Sheldon's female guest is human, Sheldon reminds him that pets are banned under the roommate agreement, with the exception of service animals and, one day, cybernetically-enhanced helper monkeys.

Quotes (34)

Howard: Are you planning on kidnapping a woman?
Sheldon: Sarcasm?
Howard: Yes, but mixed with genuine concern.

Howard: I have a two-part question.
Sheldon: Go ahead.
Howard: A: Are you kidding? And B: Seriously, are you freaking kidding me?
Sheldon: A: I rarely kid, and B: when I do kid, you will know it by my use of the word "Bazinga".
Howard: So you're saying the two of you are going to be sleeping in the same bed?
Sheldon: Yes. Bazinga.

Sheldon: Pee for Houston, pee for Austin.
Pee for the state my heart got lost in.
And shake twice for Texas.

Sheldon: Good night. And if there's an apocalypse, good luck.

Raj: Okay, show of hands: who's up for this?
(Howard eagerly raises his hand)
Leonard: We'll all be naked, in front of each other.
Howard (lowering his hand): I'm out.

News Stories

Title Date Posted
Episode 3.21 Ratings May 11, 2010

Last night's episode finished first in key demographics, coming second in total viewers.  Full story

CBS Announces Episode 3.21 April 13, 2010

CBS announces episode 3.21 to air May 10th. Judy Greer guest stars.  Full story


The guys are stunned when Sheldon informs them he will be having a female guest, Dr. Elizabeth Plimpton - a noted physicist, stay over. Sheldon quizzes Penny about the "female hygiene product" he bought for his guest, while Penny is just as puzzled as the guys at Sheldon having a female visitor.

As Sheldon welcomes Dr. Plimpton to the apartment, a nervous Leonard fears he made a fool of himself. After Sheldon shows Dr. Plimpton to her room and explains the apartment's emergency procedure, she goes to Leonard's room and starts flirting with him. The next morning, Sheldon wakes up to find a smiling Leonard and Elizabeth. When Penny comes over for a ride to work, she is introduced to Elizabeth and immediately picks up on what happened over night. Sheldon is shocked to hear that Leonard betrayed him.

At the cafeteria, Leonard is dropping hints about his enjoyable night, but the guys are not picking up his subtle clues. When Sheldon arrives with Dr. Plimpton, she immediately starts flirting with Raj. That night, Howard turns up at Raj's apartment for Halo night, but Raj tries to brush him off. When Howard finds Dr. Plimpton there, she invites him in for a "role-playing game". When Leonard arrives, she invites him in too. The guys consider the rare opportunity they've been presented with, but ultimately decide they don't want to see each other naked. Raj tricks Howard and Leonard into leaving the apartment, then continues his night with Elizabeth.

Later, Leonard tries to explain his amorous encounter to Penny, but she tells him he doesn't owe her an explanation. When Leonard persists in explaining it to Penny, his reasoning for his sexual encounter is "She let me.".

Comments (16)

Glenn Canada, 23:30 Sep 2 2012.
I love Judy Greer in this episode, I don't going around saying if a girl is hot, but she comes really close. She is way cuter than Penny/
rhiannon United Kingdom, 17:55 Aug 16 2012.
Oh i love sheldon
Jocelyn Moras Mexico, 01:04 Jan 9 2012.
I bought all the Big Bang seasons, and there are not all of the episodes included. i.e. Season 3 has 23 episodes and in the DVD just has 20. Where should I get the rest? why no one says that the DVD has not all of the episodes of the season?
LIDIA Mexico, 22:29 Aug 3 2011.
They really make me laugh as usual jajaja, ....they're great ! I like so much this episode LOL
Owen South Africa, 06:25 Jun 18 2010.
Oscar Peru, 01:18 May 19 2010.
Asi como en friends, los tenian q haceer terminar y pasaran por varias parejas. ALtas y bajas hasta que al final se queden juntos
adriapou United States, 22:48 May 12 2010.
This was not the best episode but it was still funny. I was upset to hear Wolowitz say he and Bernadette broke up. I love her and the 2 of them together. And yes, I want Leonard and Penny back together!
Erin United States, 18:01 May 12 2010.
I didn't think it was that bad. It's definitely not the best, but I found it real funny. @andres, nope, Leonard and Penny are no longer together @someguy, and yeah, a msg in Spanish is not likely here since the site politely requests posts to be in English. Peace out!
FENIX27 Mexico, 10:51 May 12 2010.
irycio Poland, 09:00 May 12 2010.
Agree with Mike, definitely the worst episode ever :/

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