Involuntary muscle contractions

A Professor was giving a lecture on ”Involuntary
Muscular Contractions" to his first year medical
students. Realizing that this was not the most
riveting subject, the Professor decided to lighten the
mood slightly.

He pointed to a young woman in the front row and
said, "Do you know what your a** hole is doing while
you're having an orgasm?"

She replied, "Probably deer hunting with his buddies."

The professor laughed so hard he could not continue
with the class.