Sheldon: See, sometimes I wish I could invent a time machine, so I could go back and prevent myself from acting so rashly.
Leonard: Or moving forward, you could think before you speak.
Sheldon: I suppose so.
Leonard: But the time machine thing is probably more likely.

Sheldon: My problem is that I don't always know when I've gone too far.
Leonard: Well, uh, if you like, I could try to help you out. You know, and maybe let you know if you're crossing a line.
Sheldon: Oh, you mean, like, with a code word?
Leonard: Sure. How's "shut up"?
Sheldon: That's perfect. People say it to me all the time, no one will suspect.

Stuart: Uh, Bernadette said you weren't crazy about the book.
Howard: No. It's great. I just don't want anyone to ever see it or read it or know it exists.

Howard: Well, look, what if we made a few changes?
Stuart: Uh, sure, yes. What-what do you have in mind?
Howard: Well, nothing major. But see here on the cover, where it says "frightened little," what if, I don't know, it didn't say that?
Stuart: So, it would just be The Astronaut?
Howard: Yeah, you're right. That doesn't quite pop. What about The Brave Astronaut? See, that's got some zip to it!
Stuart: Okay.
Howard: And here on this page, where I'm crying. What if, instead, I'm punching a meteor into the sun with my bare fists?
Stuart: So you have superpowers?
Howard: I like the way you're thinking.

Leonard: Professor Thorne?
Kip Thorne: Dr. Hofstadter.
Leonard: Uh, you know my wife, Penny.
Kip Thorne: Sure. Hi.
Penny: Hi.
Leonard: Uh, we wanted to talk to you about Dr. Cooper. Now, before you say no-
Kip Thorne: No.
Leonard: Well, then, after you say no.
Kip Thorne: No.

Penny: Okay, look, Sheldon's a pain in the ass. But Dr. Fowler's really nice. So if you average them out - math - you got someone who's okay.
Leonard: But more than the person, the Nobel is about the work. You should understand that more than anyone.
Penny: Yes, because of your work on gravitational waves.
Kip Thorne: You know my work?
Penny: I do. But I'm-I'm really hogging this conversation. Leonard?

Leonard: Just give them a chance. Uh, science has a history of difficult people. Look at, uh, Newton, who was a jerk to Leibniz, and Leibniz, who was a jerk to everyone.
Penny: Yeah, you know, and I don't need to tell you that gravitational waves are disturbances in the curvature of space-time. Or that the- Hey, you worked on the movie Interstellar?

Stuart: But this could be really good for me, you know? Finally get my artwork published. And-and come on, it's a, it's a cute story.
Howard: Oh, easy for you to say. No one's gonna think you're a coward.
Stuart: Are you kidding? The other day in the comic book store, a balloon popped and I threw up.

Howard: They're still asleep. Apparently, when I put someone down for a nap, they sleep hard.
Raj: That's a weird brag, Howard.

Bernadette: I don't know what it is about that guy, but he just gets on my nerves.
Penny: Well, you scared the bad man away. Who's a good girl?

Penny: Okay. Let's everyone calm down. If you can't find a pill for that here, then you're not trying hard enough.

Bernadette: Oh, don't waste your time. His name is Danny. He works for one of the other drug companies.
Danny: Hey, nothing wrong with checking out the competition.
Bernadette: Aw, we don't see you as competition.
Danny: You should. Our anti-inflammatory is hitting the market this year, too.
Penny: Well, ours has zero drug interaction risk.
Danny: Yeah. So does an Altoid.
Bernadette: Speaking of Altoids, why don't you go get one?

Howard: What do you say? We'll play some board games. It'll be like a party.
Leonard: Three guys playing a board game doesn't sound like much of a party.
Howard: [chuckles] Someone doesn't remember college very well.

Sheldon: No offense, Howard, but I don't want to spend my weekend around your loud, sticky babies.
Howard: You can't insult my kids. I am offended.
Sheldon: No, you can't be. I said "no offense." That's like "no backsies" but for offense.

Bernadette: See? You're doing great.
Penny: Yeah. Mediocre actress, great drug pusher. Who knew?