The Communication Deterioration - S8-E21
Penny: You are a wise man.
Sheldon: Well, Penny, who's smarter, the wise man or the person who comes to him for advice?
Penny: Oh, I guess you're right. Maybe it is the person who asks.
Sheldon: No. It's the wise man. That's why he's called the wise man. You know how I know that? I'm the wise man.