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.