A professor at the University was
giving a lecture on involuntary
muscular contractions' to his first
year medical students.

Knowing it
wasn't the
most pleasant
topic, he made
an effort to try
and lighten the
mood a bit.
He pointed to a young lady sitting
in the front row and said, "Do you
know what your asshole is doing
while you're having an orgasm?"
She
answered,
"Probably out hunting with his asshole buddies."