This is what u did.

A little boy walks into his parents' room
Then wears a quizzical frown
When he see his Mom on top of his Dad
Bouncing up and down.

The mother quickly dismounts,
Worried about what her son saw
She dresses quickly and goes to find him.
Standing outside the door

He asks, 'What were you doing to Dad just then?'
She replies, 'Well, you know Dad is fat
He has a big tummy so sometimes
I get on top and make it flat.'

'Well, you're just wasting your time, Mom,'
She is told by her bright young pup
Cos when you got out, the lady next door
Gets on her knees and blows it back up.'