Penny: Is everything okay?
Leonard: No, I found a paper that proves their theory wrong. They thought this was gonna be their Nobel Prize. It's gonna break his heart.
Penny: Oh, man. Maybe leave an anonymous note, you know, like in high school, when you want to let your best friend know that her boyfriend's cheating on her.
Leonard: Why wouldn't you just tell her that?
Penny: I don't know. Maybe you had a hickey.
Leonard: Isn't it better to get bad news from a friend?
Penny: Trust me, it's not. I went to prom with a hickey and a black eye.