Mom: Flashing my slutty bits from time to time is just part of your bully's obedience training. Listen son, I have to be a proper bimbo slut for him. Making his dick feel good is more important than your feelings.
I think we have a messed up family. When most parents find out their two sons are fucking they try to stop it right? Then why do our mom and day say we'd only not get in trouble if they couldn't watch?