Can I ride?

A couple were in thier bed ready to make love when their four year old son walked in an asked "Daddy can I ride on your back", The Dad said no, when the wife told her husband it's OK honey he doesn't know whats going on, so he agreed.

As they got in to the throws of passion and the wife started moaning and breathing heavy the little boy said, Daddy you better hold on yesterday when she did that me and the Milkman both almost hit the floor.