Penny: All right, Sheldon, this craziness has gone on long enough. Please come home so I can cut your hair.
Sheldon: Penny, you're not trained. You're not licensed. Most importantly, you don't have access to my haircut records.
Penny: All right, honey, look, we've known each other for a long time now, right? I've taken you to Disneyland, I kicked a bully in the nuts for you, I sing you Soft Kitty when you're sick. You even saw me naked once.
Leonard: I'm sorry. Uh, what?
Penny: It was a long story. Anyway, Sheldon, I promise I know what I'm doing. Please let me cut your hair.

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

Penny: I mean, who even reads Scientific American?
Leonard: It's kind of a big deal.
Penny: If it's such a big deal, how come the biggest celebrity they could get for the cover is a molecule?

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

Sheldon: Gotta run. (Looks down at scissors) But not with scissors, that would be unsafe.

Sheldon: Bongo solo!

Penny: Where are you going?
Sheldon: Wherever the music takes me, kitten.