Sheldon: You know what they say, fool me "N" times, where "N" equals the amount of times you've already fooled me, shame on you. Fool me "N" plus one times, shame on me.

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.

Penny: I'm not leaving you for Bill Gates.
Leonard: You sure? I bet his Internet's really fast.

Leonard: Uh, M-Mr. Gates, I'm-I'm Dr. Leonard Hofstadter. We've actually met before.
Bill Gates : Sorry, I don't remember.
Leonard: You were so nice, a-and it was really special to me because you've been such a big influence on my life. I mean, ever since I was a little kid, I've looked up to you like-like a hero. (sobbing)
Bill Gates : Oh, now I remember. Would you like a tissue?
Leonard: How about a hug?
Bill Gates : How-how about a tissue?

Raj: But why do they still call Batman using the Bat-Signal? Wouldn't it just be, like, easier to text him?
Howard: The Bat-Signal isn't just to alert Batman, it's also to strike fear in the hearts of his enemies and let them know he's coming.
Leonard: Sort of like Sheldon's knock.
Sheldon: Comparing me to Batman? I'll take it.