Little Johnny hears what can only be described as the throws of passion and dashes into the bedroom.
"I'll save you, mom!
His father starts laughing and tells the kid, "We're just havin' some fun, now get outta here!"
Fifteen minutes later there's a racket coming from Granny's room and when Dad opens the door johnny is bangin' the hell out of granny.
"What are you doing?" says Johnny's father, "Stop that right now!"
Johnny replies, "Not funny when it's your mom is it!?