Penny: Um, you know it's kinda early. Do you wanna maybe come in for some coffee or something?
Stuart: Oh gee, its a little late for coffee isn't it?
Penny: Aw, you think coffee means coffee. That is so sweet.

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

Raj: [to Amy] If you were having Sheldon's baby, would you really want him in the room?
Penny: Yeah, if he's in the room when they're making the baby, I'll give you $10.

Penny: I mean, who even reads Scientific American?
Leonard: It's kind of a big deal.
Penny: If it's such a big deal, how come the biggest celebrity they could get for the cover is a molecule?

Stuart: Oh, Sheldon, I'm afraid you couldn't be more wrong.
Sheldon: More wrong? Wrong is an absolute state and not subject to gradation.
Stuart: Of course it is. It's a little wrong to say a tomato is a vegetable, it's very wrong to say it's a suspension bridge.

Wolowitz: I'm a horny engineer, Leonard. I never joke about math or sex.

Howard: Are you familiar with the Drake Equation?
Sheldon: The one that estimates the odds of making contact with extraterrestrials by calculating the product of an increasingly restrictive series of fractional values such as those stars with planets, and those planets likely to develop life? N equals R times FP times NE times FL times FI times FC times L?
[pause]
Howard: Yeah, that one.