Leonard: I'm glad you decided to stay. It's gonna be special for Penny and me to share this with you.
Beverly Hofstadter: I can't wait for this day to be over.
Leonard: Yeah, special, like that.

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: 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.

Raj: Can we take a moment to discuss that I just lied to the government for you?
Howard: Yeah, I would not have done that for you.

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: Do you think your father's doing unspeakable things to my mother?
Leonard: No.
Sheldon: Are you saying that because the things are unspeakable?
Penny: Your parents are old. Anything unspeakable was finished by 9:30.