Sheldon: This is the temperature you agreed to in the roommate agreement.
Leonard: Aw, screw the roommate agreement!
Sheldon: No, you don't screw the roommate agreement. The roommate agreement screws you.

Mrs. Wolowitz Howard, are you having a playdate?
Howard: I don't have playdates. I have colleagues.
Mrs. Wolowitz Do their parents know they're here?
Howard: No, but if you keep screaming, maybe they'll hear you.

Leonard: You know what, go to Hell and set their thermostat.
Sheldon: I don't have to go to Hell. At 73 degrees, I'm there already!

Sheldon: I assure you, you'll be sorry that you wasted your money on an iPod when Microsoft comes out with theirs.
Rajesh: Do you have an opinion about everything?
Sheldon: Yes.
Howard: And you just assume you're right?
Sheldon: It's not an assumption.

Sheldon: When do you evacuate your bowels?
Leonard: When I have to.
Sheldon: When you have to? I'm sorry I don't rent to hippies.

Sheldon: What's the sixth noble gas?
Leonard: Uh, radon?
Sheldon: Are you asking me or telling me?
Leonard: Telling you?
(Sheldon gives Leonard a stern look)
Leonard: Telling you.

Sheldon: Oh, Ubuntu. You're my favorite Linux-based operating system.

Leonard: Can I sleep on your couch tonight?
Penny: Well, you can try. But the neighbors across the hall are being very noisy.
Leonard: Oh, you heard that, huh?
Penny: Yeah, apparently the one fella changed the thermostat, and then the other fella went bat-crap crazy.

Leonard: Not only that Sheldon saved my life, but that he didn't report me to the landlord, or the police, or homeland security.

Leonard: Hey. Excuse me, I'm looking for a Dr. Sheldon Cooper.
Asian Guy: Oh, so you're here about the room?
Leonard: Yeah.
Asian Guy: Run away, dude.
Leonard: Wait. What?
Asian Guy: Run fast, run far!

Penny: Okay, Babydoll Pink, let's see if you can cover up the fact that I got my dad's feet.

TV Announcer: Up next Babylon 5.
(Sheldon looks at Leonard)
(Penny listening to Sheldon and Leonard argue from her apartment)
Leonard: You're not even watching it.
Sheldon: I can hear it.
Leonard: The dialogue offends you?

Sheldon: And next, if either of us ever invents time travel, we agree our first stop will be this meeting today in precisely five seconds.
Leonard: Okay. [They look around, nothing happens]
Sheldon: Well that's disappointing.

Leonard: You know what, go to Hell and set their thermostat.
Sheldon: I don't have to go to Hell. At 73 degrees, I'm already there.

Sheldon: Last question. In a post-apocalyptic world, which task would you assign the highest priority? Locating a sustainable food source, re-establishing a functioning government, procreating, or preserving the knowledge of mankind.
Leonard: Uh, I'm gonna go with preserving the knowledge.
Sheldon: That's correct. FYI, I would have accepted any answer other than procreating.

Sheldon: Roommates agree that Friday nights shall be reserved for watching Joss Whedon's brilliant new series Firefly.
Leonard: Does that really need to be in the agreement?
Sheldon: We might as well settle it now, it's going to be on for years.

Leonard: Two degrees, Sheldon. I just want to turn the thermostat two degrees.

Leonard: Dr. Cooper?
Louis: No, you want the crazy guy next door.

Leonard: There you go, three against one.
Sheldon: They don't get a vote. It's one against one. And according to the roommate agreement, all ties will be settled by me.
Leonard: But I said no to that.
Sheldon: And I said yes. And I settle all ties.

Leonard: Do I get some sympathy now?
Penny: A little bit. Okay. Let me get this straight. You move in with this guy, he makes you sign a ridiculous roommate agreement, then he walks into your bedroom while you're doing this Joyce Kim, and you still stay?
Leonard: Actually, I couldn't get too mad at him about Joyce Kim.
Penny: Why not?
Leonard: Well, I was doing some government research at the time, you know, military, rocket fuel. It's kind of secret.
Penny: What does that have to do with Joyce Kim?
Leonard: As it turns out, she was a North Korean spy. Luckily, Sheldon drove her out before I revealed anything important. Which I'm not saying I would have.

Sheldon: (Knock * 3) Leonard?
Leonard: Shh. Just pretend we're not here.
Sheldon: (Knock * 3) Leonard?
Leonard: I'm sure he'll go away.
Sheldon: I'm just going to keep knocking till you answer. (Knock * 3) Leonard? (Knock * 3) Leonard? (Knock * 3) Leonard?
Leonard: What do you want? I didn't say come in!
Sheldon: You asked what I wanted. I wanted to come in. I'm here because you violated our roommate agreement. Specifically, section eight, visitors, subsection C, females, paragraph four, coitus. Roommates shall give each other 12 hours notice of impending coitus.
Leonard: I didn't even know her 12 hours ago.
Joyce Kim: That's it! I'm out of here!
Leonard: But, Joyce, come on.
Sheldon: 12 hours? [Looking judgmentally]

Penny: Why on earth did you agree to all that?
Leonard: It was the best apartment I'd seen, the rent was very reasonable and after you've passed the first three barriers you kind of want to take it all the way.
Penny: Well, I'm sorry, Leonard, it's very hard to feel sympathy for you.

Sheldon: Let me point out that two degrees can be the difference between water and steam.
Leonard: Yes, if we lived in a tea kettle.

Sheldon: Section nine, miscellany. The apartment's flag is a gold lion rampant on a field of azure.
Leonard: We have a flag?
Sheldon: Never fly it upside down unless the apartment's in distress.

Sheldon: That's where I sit.
Leonard: What's the difference?
Sheldon: This seat is ideally located both in relation to the heat source in the winter and a cross breeze in the summer. It also faces the television at a direct angle allowing me to immerse myself in entertainment or game play without being subjected to conversation. As a result, I've placed it in a state of eternal dibs.

Sheldon: Third barrier passed. You have won the right to see your room. Huzzah!
Leonard: Is this it?
Sheldon: No, this is my room. People don't go in my room.
Leonard: So where do you sleep?
Sheldon: I don't understand.
Leonard: If people don't go in there, and you're people, and… You are people, aren't you? Making a joke.
Sheldon: Do you do this often?
Leonard: On occasion.

Sheldon: That's correct. FYI, I would have accepted any answer other than procreating. Come, I'll show you the rest of the apartment.
Leonard: Oh, good. I passed the barriers.
Sheldon: The second barrier. Don't get cocky.

Leonard: Oh, this is pretty nice. Uh, the bedrooms are back there?
Sheldon: That depends.
Leonard: I don't understand, their, their existence is conditional?
Sheldon: No, but your ability to perceive their existence is conditional on you passing the second and third barriers.
Leonard: There's three?
Sheldon: Each more daunting than the last. Have a seat.

Sheldon: All right, next question. Kirk or Picard?
Leonard: Oh, uh, well, that's tricky. Um, well, uh, Original Series over Next Generation, but Picard over Kirk.
Sheldon: Correct. You've passed the first barrier to roommate-hood. You may enter.

Sheldon: Wait, let me get my jacket.
Howard: You're not going with us.
Sheldon: Why not?
Raj: You're the guy we're trying to get away from.
Sheldon: Oh. Well, in that case, I don't need my jacket. And for the record, the correct syntax is I'm the guy from whom you're trying to get away.

Leonard: I did notify you.
Sheldon: Oh, you did, did you? Oh, drat. Hoisted by my own spam filter.

Penny: So Sheldon's last roommate tried to warn you off?
Leonard: For all I knew, he was the crazy one. He had this really deranged look.
Penny: Well, yeah. He'd been living with Sheldon.

Sheldon: Cathedra mea, regulae meae. That's Latin for my chair, my rules.

Leonard: Not only did Sheldon save my life, he didn't rat me out to the landlord. Or the police. Or Homeland Security.
Penny: Okay, so, basically, you're the reason I have to walk up and down three flights of stairs every day?