Leonard: Look, I appreciate your signature blend of concern for me and incredible selfishness. If I get the chance to do this, there is nothing you can say that's going to stop 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: Sheldon's nervous about me leaving. Just keep an eye on him while I'm gone.
Penny: Oh, I don't know. Remember what happened when I took care of your goldfish?
Leonard: Well, flush Sheldon down the toilet and get me a new one.

Raj: Okay, I have a request to make.
Amy: And now he can talk. I want to cut open your brain and see what the heck is going on in there.

Bernadette: You know, one of the things that helped me get through Howard being in space for so long was getting married before he left.
Penny: Bernadette, sweetie, shut up.