Sheldon: Leonard, in the world of theoretical physics, you never finish; so much is unprovable.
But when I was studying that railway guide, it was so tangible and so satisfying that something just clicked. Then it clacked. Then it clicked, then it clacked, click-clack clickety-clack, and here we are. Whoo-whoo!

Bernadette: Stuart, don't you drink my milk!

Raj: You know, I just read a study that suggests new mothers are better at sensing emotions for up to two years.
Amy: It's true. Pregnancy causes physiological changes in the brain that result in increased empathy.
Penny: Huh. So all we need to do is get Sheldon knocked up.
Leonard: We can't. He was already fixed when I found him at the shelter.

Howard: I'll make you a deal. Thirty years from now, if you're still single and things don't work out with me and Bernadette you and I can give it a go.
Raj: I appreciate the offer, but if things don't work out with you two, I'm swooping in on her like a vulture.
Howard: Too late. Stuart called dibs.

Penny: Look, we got really angry at each other, and you just got caught in the middle of it.
Leonard: And sorry about the suitcase.
Sheldon: Yeah, well, you should be. Your socks were still in it. I had to throw it away.

Leonard: We owe you an apology.
Sheldon: Oh, it's fine. You needed a suitcase, I wasn't home, you borrowed a suitcase.
Leonard: That was six years ago. I'm talking about tonight.
Sheldon: Oh, well, I thought we were going in order.

Raj: Okay, maybe we should just end this.
Howard: Wait, hang on. I just want to point out to everyone here, this is a man who is going to great lengths to better himself. Even at the risk of being humiliated. And I, for one, think that's very brave.
Raj: Thank you, Howard.
Emily: Honestly, I'm surprised you two didn't wind up together.
Howard: Well, like you gals, I had to suffer through him to find Bernadette.

Emily: You know, the same thing happened to me. After I broke up with Raj, I met Gary, who's just amazing.
Howard: Sorry, is that "Gary" with one R or two?
Raj: Would you stop writing?!

Raj: So, what should we do today?
Bernadette: Oh, I appreciate it, but you don't have to spend your day off with me.
Raj: Well, I don't mind. Oh, you want go to the mall and look at baby stuff?
Bernadette: Not really.
Raj: Oh, come on, we could share a pretzel and get sideways glances from racist old ladies.
Bernadette: I get enough of that when I take Howard to my grandmother's for Christmas.

Howard: (Interpreting for Emily #1) "I thought you were great, but, oh, my God, you were so dominated by your parents."
Emily #2: Oh, yeah, and that used to drive me nuts. He's kind of a mama's boy.
Claire: Kind of?!
Raj: Whoa, okay! That's enough. (To Howard) Write down "loving son."

Leonard: Tonight he wants to look at ladders at Home Depot.
Raj: Oh, why does he need a ladder?
Leonard: He doesn't; he just likes looking at them. Bring a book.

Leonard: I don't want to play a game, Sheldon.
Sheldon: Wow, and I remember when you loved playing games with me. Maybe Penny isn't the only relationship you're phoning in.

Amy: I'll call you when we get to the hotel.
Sheldon: And if they have any of those tiny bottles of shampoo?
Amy: I will bring them home so you can show me how Godzilla takes a shower.

Sheldon: You're sad, so I made you tea.
Leonard: Thanks.
Sheldon: And it's just the way you like it.
Leonard: Earl Grey?
Sheldon: Yes.
Leonard: Honey?
Sheldon: Yes.
Leonard: Unsweetened almond-
Sheldon: Good Lord! I made you tea. Just drink it!

Ramona Nowitzki: Are these all from Peter Higgs?
Sheldon: Hmm? Oh, no, no, no. They're from many famous people. See? Oh, like this one. This is from Patrick Stewart. It says if I come to his house again, I get to meet his dogs.