Sheldon: I also was certain HD-DVD would win out over Blu-ray.
Amy: How old were you then?
Sheldon: Old enough to know better!

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: I like the Wii.
Sheldon: Thanks, Grandma.

Sheldon: Oh look, a quarter!

Sheldon: Boy, do I have to urinate.
Leonard: If only there were a solution to that.