Leonard: Oh, you do what you want, but I don't want to lose my friends over tenure. Friends are forever.
Howard [coughing]: So, is tenure.

Way to hit'em with both barrels.

Seriously, is that tape? Like, how are they staying up like that?

Amy

Leonard: You realize you might kill some of them.
Penny: Oh, then you all can get tenure.

Leonard: Mmm, you know, we could throw a dinner party too. Maybe even ask everyone to get dressed up.
Penny: Sure. Just when you say "dressed up" you mean nice clothes, right? Not, like, capes and tights and crap
Leonard: Although...
Penny: No.

Howard: Last time I was here, I was a scrawny little nerd.
Leonard: And, now, you're also an astronaut.

Sheldon: I believe in a gender blind society like in Star Trek. Where women and men of all races and creeds worked side-by-side as equals.
Leonard: You mean where they were advanced enough to develop an interstellar warp drive, but a black lady still answered the space phone?

Leonard: Helping women?
Sheldon: Helping anyone. People should take care of themselves.
Leonard: Oh, like yesterday when you made me drive you to the dry cleaners, the pharmacy and the post office?

Penny: Leonard Hofstadler...
Leonard: Yes?
Penny: Will you be my valentine?
Leonard: Sorry. Maybe, next year. ... I'm just kidding. Romance ninja. Let's have sex! Wah!

I'm cool with surprises, but nothing on the Jumbotron. I don't want to cry on the big screen like that.

You have to propose to me.

Leonard: You know what? That was pretty crappy of you. All I wanted to do was to give you a great night and it was like you went out of your way to destroy it.
Penny: Yeah, I know. I'm a total bitch.
Leonard: I'm not saying that.
Penny: Well, I am.
Leonard: Oh, fine you win. You're a bitch.

TBBT Quotes

Penny: Here's a question-- as an alien pretending to be human, are you planning to engage in any post-prom mating rituals with Amy?
Sheldon: There are post-prom mating rituals?
Penny: Not always. Unless your date drives a van with an air mattress, then always.
Sheldon: Well, if it's part of the prom experience, then I'm open to it.
Penny: You're kidding.
Sheldon: I may be an alien, but I have urges.If Amy wants to copulate by firing her eggs into space, well, then, I will happily catch them with the reproductive sac on my upper flermin. I'm not the best at reading facial cues, but I can see that you're a little turned on.

Penny: Hey, Sheldon, did you change your Wi-Fi password again?
Sheldon: Yes, it's "Penny, get your own Wi-Fi." No spaces.