Bernadette: When's he coming?
Penny: Uh, he gets in on Sunday, and Monday morning, I'm gonna give him a tour of the labs and offices.
Sheldon: Oh. He gets in on Sunday, April first? (chuckles) Nice try, Penny.
Penny: What're you talking about?
Sheldon: April Fools' Day. This is another one of your classic pranks you try to pull on me every year.
Penny: Literally never pulled a prank on you.
Sheldon: Oh, really? What about last year, when you sent me that e-mail with the photo attached, but you didn't attach a photo.
Penny: That was a mistake.
Sheldon: Messing with me? Yes, it was. And this year, I am not falling for it.

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.

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.

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

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.