A Professor was giving a lecture on "Involuntary Muscular Contractions" to his first year medical students.

Realizing that this was not his most riveting subject, the Professor decided to lighten the mood slightly.

Pointing to a young woman in the front row the professor asked, "Do you know what your ass hole is doing while you're having an orgasm?"

And the young woman replied, "Probably deer hunting with his buddies."