Penny: Damn you, you rat bastard! In the olden days, I never would have known he was that stupid.

Sheldon: Woman, you are playing with forces beyond your ken.
Penny: Yeah, well your Ken can kiss my Barbie.

Leonard: What am I supposed to do?
Penny: Err, keep your mouth off other women.

Leonard: If I take it off, Sheldon wins.
Penny: Sweetie, every night you don't kill him in his sleep, he wins.

Zack: One question. How can you be sure it won't blow up?
Leonard: The laser?
Zack: The moon.

Leonard: Don't worry about the moon. We, we set our laser to stun.
Zack: Smart.
Leonard: Now, we'll be able to see the beam when it leaves, but it won't be strong enough when it comes back to be seen by the naked eye.
Zack: (chuckling) Naked.

Leonard: She didn't dump me. We were just in different places in the relationship.
Sheldon: I fail to see how a relationship can have the qualities of a geographical location.
Wolowitz: It's very simple. Leonard was living in a little town called "Please don't leave me", while Penny had just moved to the island of "Bye-bye!"