Howard: On the potty, what are you five?
Raj: It's a potty, what do you call it?
Howard: A toilet.
Raj: That's a little vulgar for the dinner table, don't you think?
Howard: And potty is okay?
Raj: Potty is innocent. Potty is adorable.
Howard: What do you do on the potty, wee-wee?
Raj: If I don't have to boom-boom.

Sheldon: I'd like you to meet Oppenheimer, Frisch, Panofsky, Feynman, Weisskopf.
Mary: Yeah, I get it. You got a lot of cats, and you gave 'em cute Jewish names.

Mary Cooper: Now, when you said on the phone he broke up with a girl, you meant an actual girl? Not something you kids whipped up in a lab?

Penny: How's your life?
Amy: Like everybody else's, subject to entropy, decay and eventual death. Thank you for asking.

Howard: Women, you can't live with them. You can't successfully refute their hypotheses.
Sheldon: Amen to that.

Sheldon: I know mother, but you're not fooling me. Every time you want to talk it means you want me listen.
Mrs. Cooper: Then stop talking.
Sheldon: Yes, Ma'am.

*Howard imitates Raj's drunken Bollywood Breakdance*
Raj: That's very offensive.
Howard: Yeah, we all thought so.

Sheldon: I was going to name him Hermann von Helmholtz, but he's so zazzy.

Sheldon: She was a girl who was my friend who is now a girl who is not my friend.
Penny: Wow. That's like the worst country song ever.

Amy: I must take responsibility, I had to stop for feminine hygiene supplies.
Leonard, Raj, Wolowitz: Oh, oh, ok.
Sheldon: I believe she's experiencing her menses.
Amy: Actually, I'm not. In order to avoid surprises, I wear them all the time.

Sheldon: That's preposterous. I'm not pining for anybody.
Mary Cooper: Oh, lamb chop. We can quibble what to call it, but I think we can both agree it's creepy.

Amy: Is he always like this when he loses?
Sheldon: Oh, yes. You should have been here for the great Jenga tantrum of 2008.
Leonard: You bumped the table and you know it.

Mary Cooper: Well, well. That's a powerful smell.

Leonard: No, she's real.
Mary Cooper: Did they sin?

Mary Cooper: Now, don't you move. I'll bring over all the food.
Leonard: No, I can do it.
Mary Cooper: Well, isn't that sweet.