Sheldon: Hang on a second, mister.
Leonard: What?
Sheldon: After you used the facilities at the gas station, did you make a purchase?
Leonard: What?
Sheldon: It's customary when using the rest room at a retail establishment to make a small purchase. Did you?
Leonard: No.
Sheldon: Here's two dollars. Go buy some beef jerky.
Leonard: I don't want beef jerky.
Sheldon: It's not about you. It's about a poor immigrant from Pakistan trying to make his way in America by working the graveyard shift at the Colorado Boulevard Chevron.
Leonard: Fine.
Sheldon: Needy Baby, Greedy Baby indeed.

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.

Bernadette: Boy, I don't know if I could be friends with Howie if we broke up.
Howard: Why not?
Bernadette: I'm a very vengeful person.
Howard: Really?
Bernadette: With access to weaponized smallpox.

Sheldon: Does anybody have any wood? Oh, come on! I just want wood. Why are you making it so hard?

Sheldon: I know he (Spock) wouldn't care for an outburst of human emotion, but oh goodie, oh goodie, oh goodie!