Penny: Or maybe, now that I'm no longer an out-of-work actress who can't pay for her own dinner, that makes you a little insecure.
Leonard: I can't believe you would say that. You know how insecure I am about my insecurities.

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.

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

Sheldon: Are they making fun of us?
Raj: Yep.
Sheldon: I miss the old days when I couldn't tell.

Penny: Hang on. You guys are going to work in a mine?
Sheldon: Why not?
Penny: You had a panic attack when we went through the car wash!

Bernadette: Speaking of new careers, how are things going with dark matter, Sheldon?
Sheldon: Oh, I have to say it's the most exciting time in the history of the field.
Bernadette: Oh, what's going on?
Sheldon: I started doing it.