Leonard: Howard brought a date?
Sheldon: A more plausible explanation is that his work in robotics has made an amazing leap forward.

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.

Mary: He gets his temper from his daddy.
Leonard: Ah!
Mary: He's got my eyes.
Leonard: I see!
Mary: All that science stuff, that comes from Jesus.

Mary Cooper: You don't hunt, do you?

Mary Cooper: I'm sorry, did I start that sentence with the words, "If it pleases your highness?"