Mandy: Maybe you should talk to a therapist about this.
Leonard: Too expensive.

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.

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.

Sheldon: Hello.
Leonard: Hey, buddy, can we have some privacy?
Sheldon: Of course. Wouldn't want to intrude. (takes red bra out of his pocket and hands it to Penny) This is yours.
Penny: Okay, when I'm done with him, I'm gonna need more information.
Sheldon: Nothing odd. I just wanted to rub Amy's nose in it.

Sheldon: Thankfully all the things my girlfriend used to do can be taken care of with my right hand.

Leonard: I'm not being weird. Am I being weird?
Sheldon: Yes. And that's coming from me.