Sheldon: A little misunderstanding? Galileo and the Pope had a little misunderstanding...
Howard: Sheldon, you remember the first few weeks we were looking for magnetic monopoles and not finding anything, and you were acting like an obnoxious, giant dictator?
Raj: I thought we were going to be gentle with him.
Howard: That's why I added the '-tator'.
Wolowitz: Raj, there's no place for truth on the Internet.
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.
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: I am not crazy, my mother had me tested.
Leonard: What were you doing at Penny's?
Sheldon: Well, we had dinner, played some games, and then I spent the night. Oh, and you'll be happy to know that I now have a much better understanding of 'friends with benefits.'
Sheldon: Ah, gravity - thou art a heartless bitch.
Wolowitz: I am a horny engineer, I never joke about math or sex.
Penny: I give up. He's impossible!
Sheldon: I can't be impossible; I exist! I think what you meant to say is, 'I give up; he's improbable'.