Leonard: Can't you see that she's using you?
Wolowitz: Who cares? Last night she pulled off her blouse and I wept.
Penny: Look, Howard, I know her, okay. She'll sleep with anyone as long as they keep buying her things.
Wolowitz: Really?
Penny: Yeah.
Wolowitz: Yay

Leonard: What's wrong?
Penny: Well, Howard and Christy are kind of hooking up in my bedroom.
Leonard: Are you sure?
Penny: Look, I grew up on a farm. From what I heard, they're either having sex, or Howard's caught in a milking machine

Leonard: Sheldon, think this through, you're going to ask him to choose between sex and Halo.
Sheldon: No, I'm going to ask him to choose between sex and Halo 3. As far as I know, sex has not been upgraded to include high-def graphics and enhanced weapons systems.
Leonard: You're right. All sex has is nudity, orgasms, and human contact.
Sheldon: My point

Leonard: If you don't like this Christy, why are you letting her stay?
Penny: Well, she was engaged to my cousin while she was sleeping with my brother, so she's kind of family

Leonard: You know, Penny, we make such a good team, maybe we could enter a couple of Halo tournaments sometime.
Penny: Or we could just have a life.

Penny: Why can't all guys be like you?
Leonard: Because if all guys were like me the human race couldn't survive

Leonard: I understand your impulse to try to physically intimidate me. I mean, you can't compete with me on an intellectual level and so you're driven to animalistic puppery.
Kurt: Call me a "puppy animal?"

Leonard: So, what happens now?
Leslie: Well, I don't know about your sex drive, but I'm probably good till New Year's.
Leonard: Oh. Okay. Thank you.
Leslie: Thank you.
Leonard: You want to make plans for New Year's?
Leslie: Whoa, Leonard, please. You're smothering me

Penny: Leonard, I didn't know you played the cello.
Leonard: Yeah, my parents felt that naming me Leonard and putting me in advanced placement classes wasn't getting me beaten up enough

Leslie: I'm glad I ran into you. The Physics Department string quartet needs a new cellist.
Leonard: What happened to Elliot Wong?
Leslie: He switched over to high-energy radiation research and had a little mishap, and now the other guys are a little uncomfortable sitting next to him

Leslie: Listen, neither of us are neuroscientists, but we both understand the biochemistry of sex. I mean, dopamine in our brains is released across synapses, causing pleasure. You stick electrodes in a rat's brain, give him an orgasm button, he'll push that thing until he starves to death.
Leonard: Well, who wouldn't?
Leslie: Well, the only difference between us and the rat is that you can't stick an electrode in our hypothalamus. That's where you come in

Leslie: Just so we're clear, you understand that me hanging back to practice with you is a pretext for letting you know that I'm sexually available.
Leonard: Really?
Leslie: Yeah. I'm good to go.
Leonard: I thought you weren't interested in me.
Leslie: That was before I saw you handling that beautiful piece of wood between your legs

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.