A man and his wife making sweet passionate love, with the lady on top are terrified to see their son walk into the room and gasp!
Stunned, the little boy asks

"Mummy what were you doing"

"Well you know Daddy's fat tummy?, i was bouncing on it to try and flatten it out"

The Little boy replies

" i don't know why you bother because when you go to work Auntie Katherine comes round and blows it back up again"