So a mentally disturbed man walks into a dentist's office.

He says, "Doc, you gotta help me! I think I'm a moth!"

"You think you're a moth??" the dentist asks.

"Yes!"

"Well you don't need a dentist... you need a psychiatrist."

"I know," says the man.

"Then what are you doing here?"

"Well, you're light was on, so..."