502 - The Infestation Hypothesis
Aired September 22, 2011

The Infestation Hypothesis

When Penny takes in furniture she found in the street, germophobe Sheldon is horrified and urges Penny to remove the chair from the building. Amy finds herself caught in the middle of the argument between Sheldon and Penny. Meanwhile, Leonard is still adjusting to his long-distance relationship with Priya and tries to spice things up between them.

Rate this episode

Guest Stars: Aarti Mann as Priya, Brian George as Dr. Koothrappali, Alice Amter as Mrs. Koothrappli

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

Director: Mark Cendrowski

Viewers: 14.65 million Households Rating: 8.7/14 Adults 18-49 Rating: 5/14

Download from Amazon.comDownload on iTunes

Episode Notes

  • The title refers to Sheldon's ultimately valid hypothesis that Penny's chair, which she took in from the street, is infested. 

> Sheldon's Spot

When Penny took in a new chair, Sheldon was initially pleased with the seat. After Penny admitted it came from the street, germaphobe Sheldon begged Penny to remove the chair from the building. Despite Sheldon's best efforts, Penny refused to get rid of the chair, until a rat inside the chair bit Amy in the keister.

> Sheldon's Knock

Sheldon uses his knock six times in this episode, five times on Penny's door and once on Amy's. Once in a daydream as he freaks out about Penny's chair. When Sheldon goes to her apartment to tell her to get rid of the chair, Penny answers the door to three of his knocks with pithy welcomes: "What's up, buttercup?", "What's word, hummingbird?" and "What's the gist, physicist?" After Shledon knocks on Amy's doors, she tells him his ritualistic knock is symptomatic of obsessive compulsive disorder, which Sheldon rejects.

Quotes (19)

Amy: You are aware that your ritualistic knocking behavior is symptomatic of obsessive-compulsive disorder?
Sheldon: Is not. Is not. Is not.
Amy: Denial. Denial. Denial.

Leonard: Sheldon, you do this all the time! You fixate on some crazy idea then blow it way out of proportion.
Sheldon: Name one time I've ever done that.
Leonard: How about the time you put GPS trackers in your garbage because you thought North Korean spies were stealing your doodles? The chicken nuggets you thought were human nuggets. The mysterious cloud that was following you around town. Or the time you put my shirt on by accident and thought you were growing again.
Sheldon: I said name one. You need to work on your listening skills.

Penny: What's up, buttercup?

Amy: Kiss me where I've never been kissed before?
Sheldon: You mean like Salt Lake City?

Penny: We are like an old married couple!

News Stories

Title Date Posted
CBS Announces Episode 5.02 August 22, 2011

CBS has announced the second episode of the fifth season. The show returns Thursday, September 22nd at 8/7c with two back-to-back episodes, the first of which was announced last week.  Full story


Leonard is having a virtual breakfast date with Priya in India, causing Sheldon to leave the apartment and go to Penny's. As Sheldon and Penny read their magazines like an old married couple, Sheldon compliments Penny on her comfortable new chair. Penny says she found it outside the building by the curb and paid a homeless guy to bring it to the apartment. Sheldon is horrified to find out it's street furniture and instantly starts undressing so he can shower in Penny's apartment. When he reaches the shower he's disturbed to find a wet Band-Aid on the shower floor, so runs out to use his own shower.

At the university, Howard is preparing his lunch with a $175,000 hydraulic thermoforming press. Howard is surprised to learn Leonard's online chats with Priya aren't of a more intimate nature, given the long distance between them. Howard encourages Leonard to spice up their regular chats or risk losing Priya to somebody back in India. Sheldon turns up asking for Leonard to check his head for lice, convinced he's caught something from Penny's chair.

Sheldon visits Penny to tell her to get rid of the chair as it poses a health risk to the building. Penny tells Sheldon she's had the slipcovers dry-cleaned and fumigated. Sheldon finds the chair's strong chemical spell reassuring and sits down, only to find thousands of bugs crawling over him. Sheldon wakes from the daydream and rushes to Penny's apartment to tell her to get rid of the chair. Leonard's in his bed room video chatting with Priya and failing badly at dirty talk. Priya gets Leonard to take of his shirt and just as she's about to return the favor, the video starts buffering. Waiting for the screen to catch up, Leonard tries small talk with Priya.

Sheldon goes to Amy's apartment to convince her to talk to Penny about her chair. Back at Howard's workshop, Leonard has concerns over the long-distance kissing device Howard has procured, which Howard and Raj disturbingly test out together. Amy and Penny are hanging out in her apartment when Amy questions the chair. Penny sees right through the ruse and is disappointed that Amy let Sheldon talk her into this. Amy jumps out of the chair, claiming something bit her in the tushy. When the girls find something moving in the cushion, they run out of the apartment screaming.

Leonard is attempting to video chat with Priya again, and starts talking dirty before Priya has the chance to explain her parents are sitting next to her. Outside the apartment building, Raj and Howard are impressed to find a free chair. They pick the chair up to take to Sheldon and Leonard's apartment so Raj won't have to sit on the floor any more.

Comments (73)

Somdev India, 09:42 May 26 2012.
Good episode...time for leonard to move on
kimber United States, 12:13 Apr 11 2012.
i love it keep up the good work! would not change a thing about it
Sophie United Kingdom, 18:01 Oct 26 2011.
Old married couple!! Why do you tease us so hard writers??
Splinter United States, 01:56 Oct 25 2011.
Starting to jump the shark, guys. Too much diversion from the original characters and going into 'personal' lives. I liked it when Raj and Howard were only seen at the University and in Leonard/Sheldon's apartment and the comic book store. Now it's too much off of the established path. And now people are saying that they want to SEE Howard's mother ... ?? !!! ??? DON"T DO IT !!!
ali Australia, 17:33 Oct 11 2011.
what is in the chair?!
Shaily Iran, 14:20 Oct 5 2011.
Oh lord i have never laughed so hard before! The french kissing scene between Howard and Raj was unbelievable! There is not much in this region that could make me laigh so i have to thank you Chuck Lorre and Bill Prady for making my third world experience a happy one!
The robot hand is stuck on you what?! Netherlands, 12:06 Sep 29 2011.
Still funny as hell!! Try to mix it up a little but as I read the upcoming episodes, it's going to be ok. (really want to c miss walowitz) Keep it up guys!!
Alex Greece, 06:50 Sep 29 2011.
A bit dissapointed with the new episodes, I hope it will get better
BAzinGaaa New Zealand, 02:01 Sep 29 2011.
To the writers!! Buck up...after watching the second episode i am almost certain that u have ran out of jokes and gud lines..too much excitement for 5th season went all in vain..feel pretty stupid.
s16 Canada, 01:42 Sep 28 2011.
Great show, good lines. Leonard is over Penny but is Penny over Leonard. She said she made a mistake breaking up but isn't doing anything about it - except making it worse. Long distance doesn't work (without a serious commitment) get Priya back.

Leave a comment

Information The comment service will be retired on March 31, 2017.

  • This small check can help us identify automated spam.