Sheldon: She's sending virtual livestock to random men on the Internet. If I have any hope of keeping them together, I need data. Specifically, I need to know exactly what Leonard did that caused you to pop an emotional cap in his buttocks.
Penny: What?
Sheldon: Again, urban slang. In which, I believe I'm gaining remarkable fluency. So, what is the down and the low? And don't worry, this is all entirely confidential, so, you feel free to include any and all shortcomings in the bedroom.

Raj: I don't like bugs, okay. They freak me out.
Sheldon: Interesting. You're afraid of insects and women. Ladybugs must render you catatonic.

Sheldon: Scissors cuts paper, paper covers rock, rock crushes lizard, lizard poisons Spock, Spock smashes scissors, scissors decapitates lizard, lizard eats paper, paper disproves Spock, Spock vaporizes rock, and as it always has, rock crushes scissors.

Sheldon: Why are you crying?
Penny: Because I'm stupid.
Sheldon: That's no reason to cry. One cries because one is sad. For example, I cry because others are stupid, and that makes me sad.

Sheldon: *knock knock knock* Leonard? (x3)
Leonard: What, Sheldon!? What, Sheldon!? What, Sheldon!?
Sheldon: Tell me what you see here.
Leonard: The blunt instrument that will be the focus of my murder trial?

Sheldon: I would ask you to find some way to suppress your libido.
Penny: I could think about you.
Sheldon: Whatever works.

Raj: Ooo.
Penny: What's the matter, Lassie? Did Timmy fall down the well?