A boy and his grandfather are fishing in a boat.
The grandfather cracks a beer and the little boy immediately asks: "Can I have some of that?"
To which is grandfather replies "Well can your dick touch your ass?"
The boy looks perplexed and says "No..."
"Well then you are not old enough for a beer."
A week later they go out fishing again and the grandfather produces a joint and begins to smoke as they coast across the lake.
Again the boy asks, but is refused when he is told he is not old enough until his dick can touch his ass.
Another week passes, and this time the boy produces a bag of cookies from his grandmother.
His grandfather asks immediately, "Can I have some of those?"
The little boy responds "Well Grandpa, can your dick touch your ass?"
The man responds shortly "Of course it can! I'm a grown man!"
To which the little boy replies "Well that's good, then you can go fuck yourself cause you ain't getting any cookies."