Leonard: Can we please have some privacy?
Sheldon: No. I'm as much a part of this relationship as you two. And I think it's high time we put all our cards on the table. For example, where is this going? Are you two ever getting married? And if so, where will we all live? Have you thought about that?

Amy: Can we maybe put the phones down and have an actual human conversation?
Sheldon: We can, but thanks to Steve Jobs, we don't have to.

Penny: So what do you think.
Sheldon: A tad asymmetrical but nothing to be worried about.

I have two Ph. D's but somehow I'm the janitor of my sister's birth canal.

Sheldon: I've seen things. Lady things.
Amy: Listen to me. That is not the way they usually look.
Sheldon: It doesn't matter. This is no way to make new humans. People coming out of people. Some kind of dirty magic show.

And turn the bedroom floor into a amniotic slip and slide

Sheldon: The second I go out of town you throw a Christmas party without me?
Amy: Yeah, kind of.
Sheldon: That's so thoughtful. You guys are the best.

Penny: Oh, that's great. You're gonna be an uncle. Uncle Sheldon.
Sheldon: No. I'll be Uncle Dr. Cooper.

Amy: It's a beautiful night. Why don't you and I go for a nice walk together?
Sheldon: Everything is just sex with you, isn't it?
Raj: Sheldon, I think you might find the support you're looking for, if you realize that relationships are a give and take. She can only be there for you as much as you are for her.
Amy: Thank you, Rajesh.
Raj: And, Amy, you need to be patient with Sheldon, instead of pressuring him to accept intimacy on your terms.
Amy: You should probably go.

Sheldon: Well, I'm not just some trained monkey dancing for coins.
Leonard: Of course not. People love trained monkeys.

I just vomited on a lot of clowns.

Bernadette's Dad: Hey, Sheldon, what do you say we go outside and throw around the old pigskin.
Sheldon: This is a Jewish house. I don't think they have pigskins.
Mrs. Wolowitz: Did someone say "pigskin"?

TBBT Quotes

Sheldon: Why do you have the Chinese character for "soup" tattooed on your right buttock?
Penny: It's not "soup," it's "courage."
Sheldon: No it isn't. But I suppose it does take courage to demonstrate that kind of commitment to soup.
Penny: How'd you see it? You said you wouldn't look.
Sheldon: Sorry. As I told you, the hero always peeks.

Penny: Hey, Sheldon, did you change your Wi-Fi password again?
Sheldon: Yes, it's "Penny, get your own Wi-Fi." No spaces.