Sheldon: Okay, stop ruining Valentine's day and order my pizza.

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: She hid my XBOX like I'm a child. And my mom got me that for my birthday so if you don't give it back, I'm telling.

Bernadette: If you like pushing buttons so much, try pushing them on the washing machine.

Howard: A micro-valentine for a microbiologist.
Leonard: From her micro-husband.