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: There's no reason to feel uncomfortable just because we've seen each other's faces and naked bodies contorted in the sweet agony of coitus. Rest assured that any aspects of our sexual relationship regarding your preferences, your idiosyncrasies, your performance, are still protected by the inherent confidentiality of the bedroom.

Leslie: Hello men. Sheldon.

Dr. Gablehauser: What colorful nickname did you call Dr. Cooper this time?
Leslie: Dr. Dumbass.

Leslie: Boy, your heart's racing. I must've really gotten you going.
Wolowitz: Well, it's partly you, partly my transient idiopathic arrhythmia.
Leslie: Sexy.

Leslie: Listen Leonard, neither of us are neuro-scientists, but we both understand the bio-chemistry of sex, ... I mean: Dopamine in our brain is released across synapses causing pleasure. You stick electrodes in a rat's brain, give him an orgasm button and he'll push that thing 'till he starves to death.
Leonard: Who wouldn't?

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: 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"?

Howard: We'll just have to face Sheldon mano y mano y mano a mano.
Leslie: Wait, you're going up against Sheldon Cooper?
Howard: Yes!
Leslie: That arrogant, misogynistic, East Texas doorknob that told me I should abandon my work with high-energy particles for laundry and child bearing?
Leonard: She's in!

Leslie: Come for the breasts, stay for the brains!

Dr.Gablehauser: Need to get that, Dr. Cooper?
Sheldon: God, no.
Leslie: Don't turn it off, you might miss the Nobel Prize Committee saying that you won "Dumbass Scientist of the Year."

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: Hey fellow scientists. Sheldon.

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?

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!