"I just flew in from the sperm bank — and boy, are my arms tired!"

Submitted for your approval: A joke.
Clean enough to tell your mother, dirty enough to be embarrassed that she laughs at it...

There was an elderly couple who wanted to have a child. They went to the doctor, and the doctor told them they were rather old to have a child, but he decided to test the man for a sperm count anyway. He gave them a jar to take home and told the man to produce a sperm sample and bring the bottle back to the office.

Two days later, the couple went back to the doctor's office. The man told the doctor there was a problem. "I tried with my right hand, and then I tried with his left hand, but no results," he said. "Then my wife tried with her right hand and also her left hand, and she even used her mouth — with her teeth in and her teeth out — but we still couldn't get the lid off the jar."