One Head and Two Wives

I am finally enjoying my sexuality course because it is the only class where sex jokes are the norm. Here is one of the more sedate ones in "Sex and Religion"

There was once an elderly man who was not satisfied with the one wife to
whom he had been married for some years. He decided to take on a second wife who
was charming and beautiful. Now, this second wife felt rather embarassed to be
seen with such an old man. So in order to make him young, she spent a lot of
time plucking out all the grey hairs that had appeared on his head. When his
first wife noticed this, she began to pull out all his black hairs one by one,
hoping to make him appear older. This contest between the two of them went on
and in the end, the man become completely bald, with neither a single grey hair
nor black hair on his head.