Sheldon: You know, the German philosopher Friedrich Nietzsche believed that morality is just a fiction used by the herd of inferior human beings to hold back the few superior men.
Leonard: Thanks, that actually does help.
Sheldon: It's worth noting that he died of syphilis.

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: More Halloween candy. Didn't you just buy a bunch of it yesterday?
Penny: Oh, yeah. That's gone. It's a rough month when Halloween and PMS hit at the same time.

Raj: (Talking to the snake) Let's go to the biology lab and find you some nice yummy mice.
Sheldon: I tried to scare an Indian with a snake. Come on, Cooper. You're better than this.

Sheldon: [jumps out of the sofa] Bazinga, punk. Now we're even!