Sheldon: Leonard, I would like us to stop fighting about our possessions.
Leonard: Well, I'd like that, too.
Sheldon: In fact, I want you to keep the apartment flag, and I'm not just saying that because it touched your genitals.
Leonard: You promise?
Sheldon: I do. And to show you that there are no hard feelings, I am willing to rub my genitals on it as well.

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: It's not my fault I'm bad at sharing; I skipped kindergarten.

Sheldon: If it's like your 3-D chess game, then you're out of your length, width and depth. Amy, get the Neosporin, somebody just got burned.

Raj: Hey, this pregnancy had an emotionally-needy third wheel way before you came along.