Sheldon: It's like when I thought there was possum in my closet. Did I sit around wondering? No, I sent Leonard in with a pointy stick and a bag.
Leonard: I killed his chewbacca slippers.

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: Ignore them, Amy. They're just jealous because they'll never have a relationship as good as ours.
Penny: Isn't this when he says "bazooka" or something?

Penny: You guys are going out two nights in a row?
Sheldon: I missed a number of date nights while I was on my train trip, and I'm contractually obligated to make them up under the terms of the relationship agreement.
Penny: That's so hot.
Amy: It's better than hot, it's binding!

Leonard: I've seen you guys ignore each other for hours, doing totally different things.
Sheldon: It's called parallel play.
Leonard: Yeah, toddlers do that.
Sheldon: Not as well as we do.