Penny: Okay, well, you know, it's just me. I'm still getting over this break-up with Kurt, and this thing with Doug would be just rebound sex.
Leonard: Ugh, don't get me started on rebound sex.
Penny: It's just, it's my pattern. I break up, then I find some cute guy, and then it's just thirty six meaningless of ... well, you know.
Leonard: I'm not sure that I do. Um, is that one thirty-six hour experience, or is it thirty six hours spread out over say, one ... glorious summer.
Penny: No, it's usually over a weekend, and trust me, you do not feel good after it.
Leonard: Well, chafing, right?
Penny: Emotionally.
Leonard: Of course, yeah, emotional chafing.

Leonard: What would you be if you were attached to another object by an inclined plane, wrapped helically around an axis?
Sheldon: Screwed?
Leonard: There you go.

Leonard: Penny, as a scientist, my job is to figure out why things happen. But I don't think I'll ever understand how someone like me could get to be with someone like you. You know maybe I don't need to understand it, I just need to be grateful. I love you, Penny.

Sheldon: This song is never going to stop. Have you ever dealt with something so relentlessly irritating?
Leonard: That's a trick question, right?

Howard: Sheldon, if you were a robot and I knew and you didn't, would you want me to tell you?
Sheldon: That depends. When I learn that I'm a robot, will I be able to handle it?
Howard: Maybe, although the history of science fiction is not on your side.

Sheldon: I think that you have as much of a chance of having a sexual relationship with Penny as the Hubble telescope does of discovering at the center of every black hole is a little man with a flashlight searching for a circuit breaker.

Sheldon: I do feel obligated to point out to you that she did not reject you, you did not ask her out.
Leonard: You're right. I didn't ask her out. I should ask her out.
Sheldon: No! No that was not my point. My point was don't buy a cat.
Leonard: No, but you're right, I should march over there and ask her out.
Sheldon: Oh, goody! We're getting a cat.