The Big Bang Theory (2007–2019)
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The Big Bran Hypothesis 

Penny is furious with Leonard and Sheldon when they sneak into her apartment and clean it while she is sleeping.


Mark Cendrowski


Chuck Lorre (created by), Bill Prady (created by) | 4 more credits »




Episode complete credited cast:
Johnny Galecki ... Leonard Hofstadter
Jim Parsons ... Sheldon Cooper
Kaley Cuoco ... Penny
Simon Helberg ... Howard Wolowitz
Kunal Nayyar ... Raj Koothrappali


Penny asks a favor of Leonard and Sheldon: to let the furniture delivery men into her apartment when they make the delivery of her recent purchase. She gives them a key to her apartment for this task. Leonard and Sheldon regret agreeing to do so when first the delivery men will not carry the delivery up the four flights of stairs, and second when they see the pigsty that is Penny's apartment, which just does not sit right with Sheldon's orderly attitude. Penny also ends up regretting asking them when Sheldon uses the key to sneak into her apartment at night when she is sleeping to tidy up, a task in which Leonard participates. Can Penny ever forgive them for violating her personal space, regardless of how immaculate the apartment looks? Written by Huggo

Plot Summary | Plot Synopsis


Comedy | Romance


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English | Russian | Italian | Hindi

Release Date:

1 October 2007 (USA) See more »

Company Credits

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Technical Specs


Sound Mix:




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Did You Know?


Sheldon (Jim Parsons) mentions the Mandelbrot Set of complex numbers. He's referring to a set of points in the complex plane that is self-replicating according to a predetermined rule such that the boundary of the set has fractal dimensions, which is most often used in the study of fractal geometry. This is part of chaos theory. Sheldon mentions this in reference to the chaos in Penny (Kaley Cuoco)'s messy apartment. See more »


The morning after cleaning Penny's apartment, Sheldon makes himself a coffee. In later episodes Sheldon does not drink coffee. Specifically The Work Song Nanocluster (season 2 episode 18), when he says "Coffee's out of the question. When I moved to California, I promised my mother that I wouldn't start doing drugs." See more »


Koothrappali: Hello. Sorry I'm late, but I was in the hallway chatting up Penny.
Wolowitz: Really? You, Rajesh Koothrappali, spoke to Penny?
Koothrappali: Actually, I was less the chatter than the chattee.
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Crazy Credits

CHUCK LORRE PRODUCTIONS, #184 Don't fall for a woman who has had sex with one of your rock n'roll heroes. No matter how emotionally evolved you think you are, you will never enjoy listening to Eric Clapton again. Don't lurk around web sites where people comment about your work unless you're drunk. Don't use emoticons. You're too old to communicate like a twelve year old girl. Don't forget that you are the product of a culture that went stark raving mad about ten thousand years ago. Adjust your thinking accordingly. Don't answer TV critics question about the state of TV comedy. It's a trap. Don't eat anything bigger than your head. True in the sixties, true today. Don't believe that crap that you're as young as you feel. Your feelings lie. Don't hug men while shaking their hand. Enough already with that. The shake/hug (shug?) is probably something Roman guys did when their empire was in decline. See more »


References Superman IV: The Quest for Peace (1987) See more »


History of Everything
Written by Barenaked Ladies
Performed by Barenaked Ladies
[Series theme song played during the opening titles]
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User Reviews

12 September 2018 | by cjyou0See all my reviews

When Sheldon knocks on the door to apologize to Penny, he knocks one time without even saying "Penny". Now I'm curious as you when his tic actually starts, or if it's a whoops on production.

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