Leonard: It's a pep talk he made when he was a kid. He gave it to me years ago and told me to save it for a real emergency.
Penny: What? You didn't break it out when he declared his room a sovereign nation and waged a trade war against us?
Leonard: His major export is talking. I didn't want that anyway.

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: Thanks, Dad. We're gonna give them hell.

Leonard: I have something that might help. It's-it's a recording of the only person whose opinion Sheldon actually respects.
Amy: Hawking? Feynman?
Leonard: No, himself.

Amy: Hey.
Sheldon: Hello.
Amy: "Fine with flags"?
Sheldon: Yes, flags, up there flapping around on poles. If you think about it, they're just the strippers of the emblem world.