An old man takes his grandson fishing...

An old man takes his grandson fishing. A little time passes before the grandfather reaches into a cooler and pulls out a beer. Noticing this, the boy goes
"Hey grandpa, can I have a beer?"
He replies, "well can your penis touch your asshole?"
"No..."
"Well then you're not old enough to have a beer!"

A little while later the old man lights a cigarette. Once again the little boy notices this and asks
"Hey grandpa, can I have a cigarette?".
The old man replies, "can your penis touch your asshole?"
The little boy replies "no"
"Well then you're not old enough to have a cigarette!"

Some time passes, and then grandson reaches into his backpack and pulls out a bag of cookies. The grandpa notices this and says,
"Are those grandma's famous chocolate chip cookies?"
The grandson replies, "yep".
"Can I have one?"
"Well can your penis touch *your* asshole?"
"Why, yes it can!" the old man replies smugly.
The boy says, "well then you can go fuck yourself, these are my cookies!"