Penny: Sheldon, you wanna take a break? Your food's ready.
Leonard: What are you doing? He's both happy and quiet. It's like seeing a unicorn and big foot at the same time.

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.

Sheldon: This song is never going to stop. Have you ever dealt with something so relentlessly irritating?
Leonard: That's a trick question, right?

Sheldon: Sheldon Cooper does not get lucky.
Amy: You and me both, brother.

Sheldon: I've got to find a way to stop this thing.
Leonard: Buddy, I don't think you can. Once it's out there, it's out there. This thing is like the science equivalent of a sex tape.
Sheldon: Frankly, I'd prefer a sex tape.
Leonard: You don't know what a sex tape is, do you?
Sheldon: No.

Bernadette: Great news. A raccoon virus just crossed the species barrier and can now infect humans.
Raj: Why is that great news?
Bernadette: In the pharmaceutical business we have a saying: mo' infections, mo' money.