Amy: I think it's really nice that you're sharing this experience with Penny.
Leonard: I thought it'd be fun to show her my old stomping grounds. I even know the exact spot where they used to stomp me.

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.

Leonard: My point is, while you're spending all this time on your own, building computers or practicing your cello, what you're really doing is becoming interesting. When people finally do notice you, they're gonna find someone a lot cooler than they thought. And for those of you that were popular in high school, it's over, sorry. Thank you. Congratulations.

Leonard: So, for the remainder of my speech, this is for the invisible kids. Maybe you never fit in. Or maybe you were the smallest kid in the school. Or the heaviest. Or the weirdest. Maybe you're graduating and you still haven't even had your first kiss. By the way, nineteen, and Geraldine Coco, wherever you are, thank you. Maybe you don't have any friends, and guess what, that's okay. While all the popular kids are off doing whatever - I don't know what they're doing because I was never there.

Howard: All right, playtime's over. Let's open this baby up.
Sheldon: Won't that void the warranty?
Howard: Sheldon, I have a master's degree in engineering. I wipe my bottom with warranties. Except for AppleCare. That pays for itself in the long run.