Sheldon: Can I at least kick down the door?
Leonard: You're welcome to try, but the other day, it took you 15 minutes to get into a FedEx box.

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: 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: 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.

Penny: Give my friend his stuff back.
Tod Zarnecki: I don't know what you're talking about.
Penny: Well then good news. Today's the day a girl's finally going to touch you in your little special place. *Kicks him in the groin*

Raj: Come on, dude, bros before ... my sister.

Sheldon: I've never said these words before, but good job, Howard.