Sheldon: I need somewhere to work in the evenings. You have a space you aren't using. Just take a look at my proposal.
Penny: (groans) What is this?
Sheldon: A rental agreement. I will only use the room for work. I won't sleep here, I won't eat your food, I won't even use your bathroom.
Leonard: So you can just walk in any time of the day or night?
Penny: Well, he does that now. At least this way we'll get paid.

Sheldon: Woman, you are playing with forces beyond your ken.
Penny: Yeah, well your Ken can kiss my Barbie.

Leonard: What am I supposed to do?
Penny: Err, keep your mouth off other women.

Leonard: If I take it off, Sheldon wins.
Penny: Sweetie, every night you don't kill him in his sleep, he wins.

Sheldon: No, the campus isn't safe at night. There's raccoons and undergrads just walking around like they own the place.

Raj: Uh, you know, my secret to making great omelets is that I beat the egg whites separately. Speaking of which, how long have you been separated? Speaking of which, how long have you been separated?
Nell: About two weeks.
Raj: That is not a lot of weeks. In fact, that's the bare minimum to get to the plural "weeks".

Howard: Look at this cute picture of Halley in the bath.
Leonard: Aw, that's great.
Howard: Want me to send it to you?
Leonard: No, on your phone it's cute, on my phone it's a crime.