Leonard: Why do I always have to carry the heavy stuff?
Sheldon: Well, it's very simple. In our ragtag of scientists with nothing to lose, I'm the smart one, Wolowitz is the funny one, and Koothrappali is the lovable foreigner who struggles to understand our ways and fails, and that leaves you, by default, as the muscle.
Leonard: One more floor, and I'd be the pulled muscle.

Raj: I don't know if I wanna play any more.
Sheldon: Because you don't have a girlfriend? Well, good lord, if that becomes a reason to not play dungeons and dragons, this game is in serious trouble.

Sheldon: Sorry, I'm late.
Leonard: What happened?
Sheldon: Nothing. I just didn't want to come.

Sheldon: The dice giveth and the dice taketh away.

Penny: What was my first strike?
Sheldon: March 18th, you violated my rule about forwarding email humor.
Penny: I did?
Sheldon: The photo of the cat who wants to "Has Cheeseburger?"
Penny: Oh, come on, everybody loves Lolcats. They're cute and they can't spell because they're cats.
Sheldon: I trusted you with my email address and you betrayed that trust by sending me internet banality. Strike one. Touching my food. Strike two.

Sheldon: (Playing Boggle) Oh, worf. Nice. Too bad that's a proper noun.

Sheldon: That's preposterous. I do not resemble C-3PO. Don't get me wrong, I'm flattered. I just don't see it.

Penny: Mmm, what smells so good?
Sheldon: That is the intoxicating aroma of Kadhai Paneer. A perfect culinary representation of the freedom this evening holds. Not only is it Indian cuisine, which Koothrappali loathes, it contains a generous helping of peanuts, which would reduce Wolowitz to a wheezing 97-pound blister. And finally, its main ingredient is paneer, a farmer's cheese that would cause Leonard to render any room uninhabitable within minutes.

Leonard: Why don't you just tell people you're a zebra?
Sheldon: Why don't you just tell people you're one of the seven dwarves?
Leonard: Because I'm Frodo.
Sheldon: Yes, well, I'm the Doppler effect.

Sheldon: My equations, someone's tampered with my equations.
Leonard: Are you sure?
Sheldon: Of course I'm sure. Look at the beta function of quantum chromodynamics. The sign's been changed.
Leonard: Oh, yeah. But doesn't that fix the problem you've been having?
Sheldon: Are you insane? Are you out of your mind? (looking at board) Are you--? Hey, look, that fixes the problem I've been having.

Leslie: I didn't know you eat here.
Sheldon: We don't, this is a disturbing aberration.

Sheldon: It has been some time since we had a woman take her clothes off in our apartment.
Leonard: That's not true, remember at Thanksgiving, my Grandmother with Alzheimer's had that episode?
Sheldon: Point taken, it has been some time since we had a woman take her clothes off after which we didn't wanna rip our eyes out.
Leonard: The worst part was watching her carve that turkey.

Penny: (Upset, about Kurt) 4 years, I lived with him. 4 years! That's like as long as high school.
Sheldon: It took you 4 years to get through high school?

Leonard: I'm gonna invite her (Penny) over. We'll have a nice meal and chat.
Sheldon: Chat? But we don't chat, at least not off-line.

Sheldon: Do you want to hear an interesting thing about stairs?
Leonard: Not really!
Sheldon: If the height of a step is off by as little as two millimeters, most people will trip.
Leonard: I don't care. 2 millime--? That doesn't seem right.
Sheldon: It's true. I did a series of experiments when I was 12. My father broke his clavicle.
Leonard: Is that why they sent you to boarding school?
Sheldon: No. That was the result of my work with lasers.