A boy and his grandpa are fishing...

When the grandpa pulls out a beer.

The boy says, "grandpa, can I have one of those?"

Grandpa says, "does your dick reach your asshole?"

The boy says, "no...."

Grandpa says, "once your dick can touch your asshole, you can have a beer."

A little while later the boy pulls out a bag of cookies.

Grandpa says, "can I have one of those?"

Boy says, "does your dick reach your asshole?"

Grandpa says, "of course!"

Boy says, "well in that case you can go fuck yourself before you get any of MY cookies!"