Little Johnny walks in on his grandfather

Little Johnny walks in on his grandfather smoking a cigar.

“May I smoke a cigar?” Asks Johnny.

The grandpa replies “Well, does your private part touch your bum?”

Johnny replied “No.” and left the room.

The next day Johnny sees his Grandpa getting into a car.

“Can I drive the car?” Asks Johnny.

“Does your private part touch your bum?”

“No.”

The day after that, Grandpa sees Johnny about to eat a cookie.

“Johnny, may I have some of your cookie?” Asked the grandpa.

“Does your private part touch your bum?”, grandpa?”

“Yep.”

“Then go bang yourself, this is my cookie.”