A kid opens his parents door to ask them a question, but finds him taking his mom from behind. The kid is in shock and is just standing there when his dad screams at him to get out and close the door.

The next day, the dad is walking by his son's room when he hears some moaning. The dad peeks in to see what the moaning is all about and he sees his son having sex with HIS mom. The dad screams at his son, "WHAT THE HELL ARE YOU DOING?!?!" To which the son replies, "It's not so fun to see someone fucking your mom, is it?"