Leonard: And this is a high-pulse laser with a BBO crystal. It's pretty cool. It emits photons in discrete bursts.
Beverly Hofstadter: Huh. Very impressive.
Leonard: But?
Beverly Hofstadter: But what, dear?
Leonard: Oh, I don't know. It's just, usually there's a "but" followed by something that makes me feel bad.

Leonard: What would you be if you were attached to another object by an inclined plane, wrapped helically around an axis?
Sheldon: Screwed?
Leonard: There you go.

Sheldon: This song is never going to stop. Have you ever dealt with something so relentlessly irritating?
Leonard: That's a trick question, right?

Leonard: Penny, as a scientist, my job is to figure out why things happen. But I don't think I'll ever understand how someone like me could get to be with someone like you. You know maybe I don't need to understand it, I just need to be grateful. I love you, Penny.

Sheldon: I'm looking over my text correspondence with Beverly and I don't see anything that would have given her offense. Nothing's ambiguous, I spell everything out. Including "laugh out loud" and "what's the fracas?"

Amy: Are you really not gonna pick up your mother?
Leonard: No. It's fine, she likes to take a cab or a shuttle. That way she can meet people.
Amy: Well, that's kind of nice.
Leonard: Yeah, she always says that a stranger is just a person whose emotional weak point you haven't found yet.
Sheldon: Your mom is the best.

Leonard: How was your flight?
Beverly Hofstadter: There were some parents with a baby. A lot of crying.
Leonard: Well, babies do that.
Beverly Hofstadter: No, it was the parents. It seems they couldn't handle some constructive criticism.