Sheldon: I couldn't sleep knowing that just outside my bedroom is our living room and just outside our living room is that hallway and immediately adjacent to that hallway is [Penny's messed up apartment]!
Leonard: Do you realize if Penny wakes up there's no reasonable explanation to why we are here?
Sheldon: I just gave you a reasonable explanation.
Leonard: No, no. You gave me an explanation. Its reasonableness will be determined by a jury of your peers.

Leonard: Most people don't sort their breakfast cereal numerically by fiber content.
Sheldon: Excuse me, but I think we've both found that helpful at times.

Sheldon: Explain to me an organizational system where a tray of flatware on a couch is valid. I'm just inferring that this is a couch, because the evidence suggests the coffee table's having a tiny garage sale.

Leonard: If you don't have any other plans, do you want to join us for Thai food and a Superman movie marathon?
Penny: A marathon? Wow, how many Superman movies are there?
Sheldon: You're kidding, right?

Raj: Are there any chopsticks?
Sheldon: You don't need chopsticks, this is Thai food.
Leonard: Here we go.
Sheldon: Thailand has had the fork since the latter half of the nineteenth century. Interestingly they don't actually put the fork in their mouth, they use it to put the food on a spoon which then goes into their mouth.
Leonard: Ask him for a napkin, I dare you.

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.

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.

*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: 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.

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: 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?

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.

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)

Leonard: How was work?
Penny: Well, you know, it's the Cheesecake Factory. People order cheesecake, and I bring it to them.
Leonard: So, you sort of act as a carbohydrate delivery system.
Penny: Yeah, call it whatever you want, I get minimum wage.

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.