Howard: He can't handle the fact that I'm a bigger deal than he is now.
Sheldon: Oh, preposterous. I have been solely responsible for this university's six loop quantum gravity calculations, I have changed the way we think about Bose-Einsten condensates, and I am also the one who got Nutter Butters in the cafeteria vending machine. Maybe you missed that news while you were floating around like a goof in outer space.

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.

Bernadette: Gosh, Amy. I'm sensing a little hostility. Is it maybe because like Sheldon's work, your sex life is also theoretical?

Howard: Are you listening to yourself?
Sheldon: I always listen to myself. It's one of the great joys of my life.

Sheldon: You know what they say. Revenge is a dish best served nude.