Sheldon: Amy is free. She had a harp lesson on Saturday, but it got canceled. Boy, when you take an interest in people, you really uncork a geyser of nonsense.

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 would pull this car over and kick you out, but if Penny dumps me, you're all I got.

Raj: No offense to her father, but he's not an MIT-trained engineer. Thinking and building is what you do.
Howard: MIT's motto is "Mind and Hand," which just so happens was also my motto as a lonely teenager.

Bernadette: Things going well with you and Sheldon living together?
Amy: Better than ever. He asks about my day, takes an interest in my life. He's like my boyfriend in college, except he's real, so people can see him.
Bernadette: I've been seeing him for years. I'm still not convinced he's real.