Leonard: Hey. Cleaning out the old dryer lint, huh? Not only is it courteous, it's safety smart. Every year, 15,000 fires are caused by accidental dryer lint ignition. Now you're supposed to say, wow, what an interesting fact. Come here, you crazy, nerdy guy. I could never be mad at you.

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?

Raj: You can't wear the hands on the date.
Sheldon: Hulk sad!

Penny: You know, I believe in ghosts, too.
Leonard: Great.
Penny: And astrology.
Leonard: I know, and pyramid power and healing crystals.
Penny: Oh, no, no, no, crystals don’t work.
Leonard: Really, that’s the line? Psychics are real, but crystals are voodoo?
Penny: Oh, Voodoo is real. You don't want to mess with Voodoo.

Leonard: How can I go out with a woman who believes in psychics?
Howard: Hey, I once dated a girl who believed she was abducted by aliens.
Leonard: And that didn't bother you?
Howard: Au contraire. It meant that she was gullible and open to a little probing.