Leslie: Listen, Leonard, 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: Who wouldn't?
Leslie: Well, the only difference between us and a rat is that you can't stick an electrode in our hypothalamus. That's where you come in.
Leonard: Yeah, well, I'm just glad to be a part of it. So what happens now?
Leslie: Well, I don't know about your sex drive, but I'm probably good till New Years.

Leonard: That's not what she's doing, Leslie. She's just trying to shore up her self esteem. It has nothing to do with sex.
Leslie: Everything has to do with sex.
Howard: Mmmm, testify. (Raises his hand for a high-five)
Leslie: I'm not touching that.

Leslie Winkle: Uh, in the past, I would've said something obnoxious, like, "Happy birthday, dumbass". But I'm not gonna do it. You and I have both grown a lot, and it's just so nice to see you all again. So happy birthday, Sheldon.
Sheldon: Oh. Oh, now, you know I hate change. Say it.
Leslie Winkle: Happy birthday, dumbass!

Leslie: Hey, are you enjoying that prototyper I got you?
Howard: Oh, it's great. Everybody in the Engineering Department is eating their hearts out.
Leslie: Isn't it nice when your good fortune makes others miserable?
Howard: You know, most people don't get that.

Leslie: So, dumbass, I heard you made a grad student throw up last night.
Sheldon: The truth can indeed be a finger down the throat of those unprepared to hear it. But why should I cater to second-rate minds?
Leslie: Because first-rate minds call you "dumbass"?

Leonard: I guess we let them wait until they're old enough and let them choose their own theory.
Leslie: We can't let them choose, Leonard, they're children!

Leslie: You agree with me, right, loop quantum gravity is the future of physics.
Leonard: Sorry Leslie, I guess I prefer my space stringy not loopy.
Leslie: Well, I'm glad I found out the truth about you before this went any further.
Leonard: Truth, what truth? We're talking about untested hypotheses, uh, it's no big deal.
Leslie: Oh, it isn't, really? Tell me Leonard, how would we raise the children?

Leslie: Hey fellow scientists. Sheldon.

Leonard: Well, I think tonight was a very good start.
Leslie: Me too. You're sure you're okay postponing intercourse until our relationship is past the initial viability test?
Leonard: No problem, I'm very skilled at postponing intercourse. So I guess I'll call you and we'll arrange another evening.
Leslie: Yes. I believe protocol dictates that you wait a minimum of 18 hours before you call so I'm not repulsed by your cloying eagerness.
Leonard: Sure.
Leslie: Again, it's your decision, you're the man.

Leslie: Hey, dummy.
Sheldon: Hello to you, insufficiently intelligent person.
Leslie: Ooh, rush me to the burn unit.

Leslie: Oh. So, how many children do you think we should have?
(Leonard splutters)
I'm sorry, that was a little abrupt.
Leonard: A little.
Leslie: I mean there are so many things to talk about before we discuss reproduction.
Leonard: I sure hope so.
Leslie: Besides shortness, what genetic weaknesses run in your family?

Leslie: Anyway, I just figure it's time to slow things down and who better to slow things down with than you?
Leonard: Oh, I'm flattered. So, how do you suggest we proceed?
Leslie: Your place, we'll order Chinese, you'll rent a movie, artsy but accessible, then light petting, no coitus.
Leonard: Sounds fun.
Leslie: I'll leave the details up to you, I think it's better if you assume the male role.
Leonard: Thank you, that's very thoughtful.
Leslie: Great. Call me!

Leslie: Wow. So, I heard your relationship with Penny crashed to the ground like blue ice falling out of an airplane lavatory.
Leonard: Where did you hear that?
Leslie: Actually I read it. Wolowitz texted me.
Leonard: (Reading the text) "Like blue ice falling out of an airplane lavatory." Yep.
Leslie: I thought it was a pretty good one, I gave him an L-O-L.

Leslie: PMS? It's a couple of days early, but
Leonard: No, it stands for Perpetual Motion Squad.
Leslie: Oh, right, of course, what was I thinking?

Leslie: Is it the waitress?
Leonard: Penny? What about her?
Leslie: Well, I thought I saw your pupils dilate when you looked at her, which, unless you're a heroin addict, points to sexual attraction.