I didn't feel a thing

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 doctor 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 doctor says, "I bet you are a surgeon".
She confirms and asks how he knew.
"Easy, you're always washing your hands."
She then says, "I bet you're an anesthesiologist."
Male doctor: "Wow, how did you guess?"
Female doctor: "I didn't feel a thing."