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.

Howard: Sheldon, don't take this the wrong way, but, you're insane.
Leonard: That may well be, but the fact is it wouldn't kill us to meet some new people.
Sheldon: For the record, it could kill us to meet new people. They could be murderers or the carriers of unusual pathogens. And I'm not insane, my mother had me tested.

Sheldon: May I say something?
Leonard: Not right now, Sheldon.
Sheldon: But I think it may be comforting.
Leonard: Buddy-
Howard: No, it's okay. What?
Sheldon: When I lost my own father, I didn't have any friends to help me through it. You do.

Sheldon: I've got to find a way to stop this thing.
Leonard: Buddy, I don't think you can. Once it's out there, it's out there. This thing is like the science equivalent of a sex tape.
Sheldon: Frankly, I'd prefer a sex tape.
Leonard: You don't know what a sex tape is, do you?
Sheldon: No.

Leonard: Our babies will be smart and beautiful.
Sheldon: Not to mention imaginary.

Sheldon: I would have been here sooner but the bus kept stopping for other people to get on it.

Sheldon: I know the real reason you never made progress with that idea. You thought of it September 22nd, 2007. Two days later, Penny moved in and so much blood rushed to your genitals, your brain became a ghost town.

Leonard: I'm not being weird. Am I being weird?
Sheldon: Yes. And that's coming from me.

Sheldon: Oh, I should probably tell you something about this gift.
Amy: You mean, before you give it to me?
Sheldon: Yes. But may I ask you a question before I give it to you?
Amy: Of course.
Sheldon: Why are we saying give it to you like that?

Leonard: I did a bad thing.
Sheldon: Does it affect me?
Leonard: No.
Sheldon: Then suffer in silence.

Sheldon: Then it's settled. Amy's birthday present will be my genitals.

Sheldon: Thankfully all the things my girlfriend used to do can be taken care of with my right hand.

Penny: Sheldon, we know this is a sensitive subject, and Leonard's not going to move out until you're ready.
Sheldon: What if you did it gradually?
Leonard: All right, how about we start with two nights a week I live with Penny?
Sheldon: How about one night and I let you whistle?
Leonard: Okay.
Sheldon: When I'm not home.