Once upon a time there was a sperm named Stanley. He'd do pushups and
somersaults and limber up all the time, while the other sperm just lay around
on their fat asses not doing a thing. One day, one of them became curious
enough to ask Stanley why he exercised all day. Stanley said,
"Look, only one sperm gets a woman pregnant and when the right
time comes, I am going to be that one."
A few days later, the all felt themselves getting hotter and hotter, and they
knew that it was getting to be their time to go. They were released abruptly
and, sure enough, there was Stanley swimming far ahead of all the others.
All of a sudden, Stanley stopped, turned around, and began to swim back with
all his might.
"Go back! Go back!" he screamed. "It's a blow job!"