A little girl catches her parents having sex. She says "mummy, why are you bouncing up n down on daddy?"
Her mummy replies "You see daddy"s big belly? I"m trying to get some of the air out of it."
The following night, she walks in on them again - this time she says
"I think you are wasting your time mummy, today I saw Mrs. Jones from next door blowing him back up again.