A little boy wakes up three nights in a row when he hears a thumping sound coming from his parents room. Finally one morning he goes to his mom and says,
"Mommy, every night I hear you and daddy making noises and when I look in your bedroom you are bouncing up and down on him."
His mother, completely taken by surprise says,
"Well, I'm bouncing on daddy's stomach because he is fat and that makes him thin again."
"Well, that won't work mommy."
"And why is that?" she asks.
"Because the lady next door comes by after you leave every day and blows him back up!"