Sheldon: Coins lodged in body parts is not a source of amusement. When I was five, Billy Sparks put a Mexican peso up my nose.
Howard: How is that not amusing?
Sheldon: It's still there. Takes me forty-fives minutes to get through airport security.

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.

Amy: Jewelry? Seriously? Sheldon, you are the most shallow, self-centered person I have ever met! Do you really think another transparently manipulative - Oh, it's a tiara! Put it on me, put it on me, put it on me, put it on me.

Penny: You look beautiful.
Amy: Of course I do, I'm a princess and this is my tiara!

Sheldon: Hard as this may be to believe, it's possible that I'm not boyfriend material.
Leonard: Glad I was sitting down for that.