Sheldon: I'm not sure how to respond, Leonard. I don't own Amy. You can't own a person, at least not since?
*Leonard stares at him*
Sheldon: 1863. When President Lincoln freed the?
*Leonard looks fed up*
Sheldon: Slaves. Come on, Leonard. If you're gonna teach history, these are the kind of facts you'll have to know.

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: I thought you didn't like Facebook any more.
Sheldon: Don't be silly, I'm a fan of anything that tries to replace actual human contact.

Bernadette: I'm too small for Twister. And roller coasters. And sitting with my feet on the floor. Hope you enjoyed the prenatal cigarettes, Mom.

(Sheldon knocks on Penny's door three times)
Penny: Who do we love?
Sheldon: Penny. (Knocks 3 times)
Penny: Who do we love?
Sheldon: Penny. (Knocks 3 times)
Penny: Who do we love?
Sheldon: Penny.