Leonard: I don't have to put up with this.
Sheldon: Actually, I have your signature on a Roommate Agreement that says you do.
Leonard: Here's what I think of your Roommate Agreement.
Sheldon: You pick that up right now.
Leonard: No.
Sheldon: Roommate Agreement, Section 27, Paragraph 5: "The Roommate Agreement, like the American flag, cannot touch the ground."

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.

Howard: If you don't leave now, she'll use food and guilt to keep you there the rest of your life.

Howard: Honestly, if I could bend that far what would I need with you.
Bernadette: If you could bend that far, you'd be doing both of us a favor.

Mrs. Wolowitz Oh please. You're a tall glass of brown water. Have dessert.