This is an oldie but a goodie.
In order to keep his teenage son from getting any girls pregnant, his father decided to warn him off sexual intercourse with women by giving him the following advice:
"Son, never go near a woman's vagina. It's a vicious thing with razor-like teeth and it will bite off your penis".
The boy remembered this piece of advice all throughout his teenage years and never once attempted to have sex with a woman.
Later on in life, still a virgin, he met a girl, fell in love and they got married.
On their wedding night, his new wife was naturally expecting sex. In bed, she made every attempt to make love to her husband. He was insistent that he was not going to make love to her for fear of having his penis bitten off by the teeth in her vagina.
She was shocked by his beliefs, and tried to coax him into sex by telling him to go down and have a look for himself, he would soon see that there were no teeth and therefore nothing to worry about.
So, the man cautiously opened her legs and went down to have a look.
After a minute his wife said "Well, do you see any teeth"?
"No" he replied "And it's no wonder......have you seen the state of your gums"?!?!