Raj: Wow, I-I know you were single back then, but that is a lot of porn-
Howard: Science! A lot of science.
Leonard: Wow, you were really into Asian science.

Sheldon: What do you think will make the wedding worse for Amy, a cake made with salt instead of sugar or a cake iced with congealed gravy?
Leonard: That is a trick question. The answer is: you as the groom.

Howard: Look at this cute picture of Halley in the bath.
Leonard: Aw, that's great.
Howard: Want me to send it to you?
Leonard: No, on your phone it's cute, on my phone it's a crime.

Penny: Well, I'm going to take myself out to a movie tonight. You want to go?
Leonard: Really? Do we do that?
Penny: What do you mean?
Leonard: You know, we haven't spent time alone together since we broke up.
Penny: Oh, it's not a date, Leonard. It's just a man and a woman hanging out, and not having sex at the end of the night.
Leonard: Sounds like most of my dates.

Penny: So, how long have you been working on this?
Leonard: Oh, couple hours. I took a break to try to beat my high score on Mario Kart.
Penny: Well, did you do it?
Leonard: Do you see it on the board?

Sheldon: Leonard, quick. I need you to get me to Arcadia within the hour. The train store's having a sale.
Leonard: Why can't Amy drive you?
Sheldon: Because of the tradition that I cannot see Amy on the day of the train store sale.
Leonard: Please, please see a doctor.

Leonard: Look, this is your wedding, just pick whoever you want. You don't need to worry about anyone else but yourself. You've kind of been training for this your whole life.

Leonard: Hey, Sheldon.
Sheldon: Hello.
Leonard: Hey. So, your contract provides for a three-day trial period, and I don't think this is working out. So, to put it in legal terms, the party of the first part would like the party of the second part to get out.

Leonard: Uh, M-Mr. Gates, I'm-I'm Dr. Leonard Hofstadter. We've actually met before.
Bill Gates : Sorry, I don't remember.
Leonard: You were so nice, a-and it was really special to me because you've been such a big influence on my life. I mean, ever since I was a little kid, I've looked up to you like-like a hero. (sobbing)
Bill Gates : Oh, now I remember. Would you like a tissue?
Leonard: How about a hug?
Bill Gates : How-how about a tissue?

Amy: What happened?
Leonard: Well, we scrubbed out some barrels of irradiated grease, rinsed off in a safety shower and then told Barry Kripke what is what.
Amy: And he just gave in?
Sheldon: Well, we agreed to invite him to the wedding.
Amy: Okay. No problem.
Leonard: And he gets to bring a date.
Amy: Well, that's reasonable.
Sheldon: A-And if she charges by the hour, we have to cover it.
Amy: What else did you agree to?
Leonard: Well, um, you know how Barry has the voice of an angel?
Amy: He is not singing at our wedding.
Sheldon: (stammers) He only wants to sing "Volare."
Leonard: Oh, "Volare". That's what he was saying. Boy, I didn't, I did not get that.

Raj: But why do they still call Batman using the Bat-Signal? Wouldn't it just be, like, easier to text him?
Howard: The Bat-Signal isn't just to alert Batman, it's also to strike fear in the hearts of his enemies and let them know he's coming.
Leonard: Sort of like Sheldon's knock.
Sheldon: Comparing me to Batman? I'll take it.

Penny: The pastrami truck moved.
Leonard: That is the danger of a restaurant on wheels.

Amy: Now, if you'll excuse me, told Sheldon I was going to the market, so I'm taking some of your stuff. [raids the fridge] I was never here.
Leonard: Sometimes you don't see it 'cause she's next to Sheldon, but she's pretty weird.

Sheldon: *knock knock knock* Dr. Wolcott? *knock knock knock* Dr. Wolcott? *knock knock knock* Dr. Wolcott? [sound of many locks clacking]
Howard: That's a lot of locks.
Leonard: Mm. That was a lot of knocks, they were made for each other.

Leonard: Listen, Sheldon, this is stupid. I don't see why we can't be friends. And I'm willing to drive you around and help you out with stuff. I just don't want to do it because of some silly roommate agreement.
Sheldon: What are you proposing?
Leonard: That we go back to the way things were. But when I do something for you, you show a little appreciation.
Sheldon: And how would I do that?
Leonard: You say thank you.
Sheldon: Every time?
Leonard: It's not crazy.