Howard: Haven't you ever been told how beautiful you are in flawless Russian?
Penny: No, I haven't.
Howard: Get used to it.
Penny: Yeah, I probably won't.

Penny: Hey Raj! (silence) Still not talking to me, huh?
Sheldon: Don't take it personally. It's his pathology. He can't talk to women.
Howard: He can't talk to attractive women, or in your case a cheesecakescented Goddess!

Leonard: Excuse me, your entire argument is predicated on the assumption that Superman's flight is a feat of strength.
Sheldon: Are you listening to yourself, it is well established that Superman's flight is a feat of strength, it is an extension of his ability to leap tall buildings, an ability he derives from Earth's yellow Sun.
Howard: Yeah, and you don't have a problem with that? How does he fly at night?
Sheldon: Uh, a combination of the moon's solar reflection and the energy storage capacity of Kryptonian skin cells.

Leonard: I have 26 hundred comic books in there, I challenge you to find a single reference to Kryptonian skin cells.
Sheldon: Challenge accepted. (Tries to open the apartment door.) We're locked out.
Raj: Also, the pretty girl left.

Sheldon: You do understand that our efforts here will in no way increase the odds of you having sexual congress with this woman?
Leonard: Men do things for women without expecting sex.
Sheldon: Yeah, those are men who just had sex.
Leonard: I'm doing this to be a good neighbor. In any case, there's no way it could lower the odds.

Sheldon: Great Caesar's Ghost, look at this place!
Leonard: So Penny's a little messy.
Sheldon: A little messy? The Mandelbrot set of complex numbers is a little messy, this is chaos.

Leonard: Did it ever occur to you that not everyone has the compulsive need to sort, organize and label the entire world around them?
Sheldon: No.

Sheldon: You might want to speak in a lower register.
Leonard: What?
Sheldon: Evolution has made women sensitive to high pitched noises while they sleep, so that they'll be roused by a crying baby. If you want to avoid waking her, speak in a lower register.
Leonard: That's ridiculous. (Penny snores.)
Sheldon: No, (lowering his voice) that's ridiculous.
Leonard: (In a lower register) Fine. I accept your premise, now please let's go.

Sheldon: I have to say, I slept splendidly. Granted, not long, but just deeply and well.
Leonard: I'm not surprised. A well known folk cure for insomnia is to break into your neighbor's apartment and clean.
Sheldon: Sarcasm?
Leonard: You think?

Sheldon: I am truly sorry for what happened last night. I take full responsibility. And I hope that it won't color your opinion of Leonard, who is not only a wonderful guy, but also, I hear, a gentle and thorough lover. (Penny slams the door in Sheldon's face)

Raj: Hello, sorry I'm late. But I was in the hallway, chatting up Penny.
Howard: Really? You? Rajesh Koothrapali, spoke to Penny?
Raj: Actually, I was less the chatter than the chattee.

*Leonard tries to slip a note under Penny's apartment door*
Penny: Hi.
Leonard: Oh.
Penny: What's going on?
Leonard: Um, here's the thing. (Reads from the note.) Penny, just as Oppenheimer came to regret his contributions to the first atomic bomb, so too I regret my participation in what was, at the very least, an error in judgment. The hallmark of the great human experiment is the willingness to recognize one's mistakes. Some mistakes, such as Madame Curie's discovery of Radium turned out to have great scientific potential even though she would later die a slow, painful death from radiation poisoning. Another example, from the field of Ebola research-
Penny: Leonard.
Leonard: Yeah.
Penny: (hugs him) We're okay.

Leonard: Six two inch dowels.
Sheldon: Check.
Leonard: One package, Phillips head screws.
Sheldon: Check.
Penny: Guys, seriously, I grew up on a farm, okay. I rebuilt a tractor engine when I was like twelve. I think I can put together a cheap Swedish media center.
Leonard: No, please. We insist, it's the least we can do considering.
Sheldon: Considering what? How great this place looks?

Howard: Oh boy, I was afraid of this.
Leonard: What?
Howard: These instructions are a pictographic representation of the least imaginative way to assemble these components. This right here is why Sweden has no space program.

Penny: Well, uh, it looked pretty good in the store.
Leonard: It is an inefficient design. For example, Penny has a flat screen TV, which means all the space behind it is wasted.
Sheldon: We could put her stereo back there.
Leonard: And control it how?
Sheldon: Run an infra-red repeater, photocell here, emitter here, easy peasy.