At a medical convention, a male doctor and a female doctor start eyeing each other. The male doctor asks her to dinner and she accepts.
As they sit down at the restaurant, she excuses herself to go and wash her hands. 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"