Little Johnny was passing his parents bedroom in the middle of the night in search of a glass of water. Hearing a lot of moaning and thumping, he peaks in and catches mommy and daddy in the act. Before daddy can even react, Little Johnny exclaims, "Oh boy! Horsey ride! Daddy, can I ride your back?"
Daddy, relieved that Johnny's not asking more uncomfortable questions, and seeing the opportunity not to break his stride, agrees...
Johnny hops on daddy and daddy gets back to businessn... pretty soon mommy starts moaning and gasping... Johnny cries out, "Hang on tight, Daddy! This is the part where me and the mailman usually get bucked off."