A man picks up a girl at a party. They proceed to her place and things start to heat up.... He takes his shirt off and washes his hands. He takes his pants off and washes hands again. So the girl tells him: "I bet you're a dentist."

Surprised he says: "That's correct, how did you know?".

"You washed your hands a few times, so I figured you're used to it ..."

They go on and they have sex. Then she says, "You know what? I'm willing to bet you're a very good dentist".

"How can you tell?" he asks.

"I didn't feel a thing..."