Leonard: Come on! We have a combined IQ of 360 we should be able to figure out how to get into a stupid building.
*Two girls selling cookies ring every bell, the door opens*
Sheldon: What do you think their combined IQ is ?

Leonard: New neighbor?
Sheldon: Evidently.
Leonard: Significant improvement over the old neighbor.
Sheldon: A 200 pound transvestite with a skin condition, yes, she is.

Leonard: What makes you think she wouldn't have sex with me? I'm a male and she's a female.
Sheldon: Yes, but not of the same species.

Sheldon: My mom bought me those pants.
Leonard: I'm sorry!
Sheldon: You're gonna have to call her.

Sheldon: So, if a photon is directed through a plane with two slits in it and either is observed, it will not go through both. If it's unobserved, it will. However, if it's observed after it left the plane, before it hits it's target, it will not have gone through both slits.
Leonard: Agreed! What's Your Point?
Sheldon: There's no point, I just think it's a good idea for a T-shirt!

Sheldon: Leonard, I don't think I can do this.
Leonard: What are you, kidding? You're a semi-pro.
Sheldon: No, we are committing genetic fraud. There's no guarantee that our sperm's going to generate high-IQ offspring. Think about that. I have a sister with the same basic DNA mix who hostesses at Fuddruckers.

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.

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.

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?

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.

Leonard: I have a board. If you like boards, this is my board.
Penny: Holy smokes.
Sheldon: If by "holy smokes", you mean a derivative restatement of the kind of stuff you can find scribbled on the wall of any men's room at MIT, sure.
Leonard: What?
Sheldon: Oh, come on. Who hasn't seen this differential below "here I sit brokenhearted"?

Kurt: How the hell did you get in the building?
Leonard: We're scientists.
Sheldon: Tell him about our IQ.

Sheldon: Um, Penny, that's where I sit.
Penny: So, sit next to me.
Sheldon: No, I sit there.
Penny: What's the difference?
Sheldon: "What's the difference"?
Leonard: Here we go.
Sheldon: In the winter that seat is close enough to the radiator to remain warm, and yet not so close as to cause perspiration. In the summer it's directly in the path of a cross breeze created by open windows, there and there. It faces the television at an angle that is neither direct, thus discouraging conversation, nor so far wide to create a parallax distortion. I could go on, but I think I've made my point.