All these sperm are hanging around.  Stanley the sperm is working out,
swimming laps and lifting weights. Everyone else is just lounging
around.

The other sperm says, " Stanley, what are you working out for?"
Stanley says, " When the time comes, I want to be the one."
The other sperm says, "What are the chances of that--one in a million?"

The time comes, and they all start swimming and Stanley is way ahead of
the pack. Then all of a sudden Stanley stops and starts swimming
backward and tells everyone to turn a round and go back.

Everybody says, "Stanley, what's the matter?"

Stanley says, "It's a blow job"