Leonard: Penny started taking a class. She wrote a paper, she didn't want me to read it, I went behind her back and I read it anyway.
Sheldon: Stephen Hawking hates me.
Leonard: I don't know what to do. I mean, the paper's terrible. But if I tell her, she'll know that I read it and she'll get really mad.
Sheldon: I was beating him so bad, he doesn't want to be friends anymore. Why does everyone love me except Stephen Hawking?
Leonard: Is it possible we're having two different conversations?
Sheldon: How would I know? I'm not listening to you.

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.

Leonard: I did a bad thing.
Sheldon: Does it affect me?
Leonard: No.
Sheldon: Then suffer in silence.

Stephen Hawking: What does Sheldon Cooper and a black hole have in common? They both suck.

Sheldon: Steven Hawking's a genius and he talks like a robot. It's everything I ever wanted in a friend.