Leonard: I worked hard on that speech, too.
Penny: Oh. You could tell it to me.
Leonard: Oh, thank you, but I'm okay.
Penny: Are you sure? I could pretend I'm a high school cheerleader who can't control herself around esteemed alumni.
Leonard: Greetings, distinguished cheerleaders.
Penny: Ooh!

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: 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.

Professor Proton: Can I ask you a question?
Leonard: Yeah, sure.
Professor Proton: Why do you put up with Sheldon?
Leonard: Oh, you know because we're friends.
Professor Proton: Why?
Leonard: Wow, you ask really hard questions. Look, I know he can be aggravating, but what you have to remember is he's not doing it on purpose, it's just how he is. But he's also loyal and trustworthy and we have fun together.
Professor Proton: You know you're describing a dog?
Leonard: He did bite me once. But in his defense, I came up behind him while he was eating.
Professor Proton: They hate that.
Leonard: Sheldon is the smartest person I have met. He's a little broken and he needs me. And I guess I need him too.
Professor Proton: Why is that?
Leonard: Boy, you will not let this go, will you?

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.