Leonard: Whatever, Sheldon. I'm exhausted. I'm not taking you to the dentist.
Sheldon: Wrong, sir. Wrong. Under section 37B of the roommate agreement, miscellaneous duties, you are obligated to take me to the dentist. See? It's right here after providing a confirmation sniff on questionable dairy products.
Leonard: You know what, I am sick of the roommate agreement. It's ridiculous. I'm your roommate, not your chauffeur. You know, I had better things to do yesterday than drive you all the way to the good model train store in Garden Grove because the one in Pasadena has gotten too big for its britches.
Sheldon: Well, it has. Ask anybody.

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: I would have been here sooner but the bus kept stopping for other people to get on it.

Leonard: You call that a glow stick? *Pulls out a Lightsaber* That is a glow stick!

Penny: Sheldon, that's not what girlfriends are for. Although you don't use them for what they're for, so what do I know?