After dinner, one thing leads to another and they end up in her hotel bedroom. Just as things get hot, the female doc interrupts and says she has to go and wash her hands. Once she comes back they go for it.
After the sex session, she gets up and says she is going to wash her hands. As she comes back the male doc says "I bet you are a surgeon."
She confirms and asks how he knew. "Easy, you're always washing your hands."
"That's very clever" she says, "I bet you're an anesthesiologist".
"Wow, how did you guess?"
"I didn't feel a thing"