Immature joke

I heard this joke in like the third grade. A guy walks into a pub and really had to take a dump. So He goes into the bathroom and takes a duke, and while he's droppin' some kids off at the pool, he notices that there is no toilet paper. And he also notices some writing with a hole underneath it and it reads, "Put your finger in the hole and someone will lick the poop off of it." So he wipes with his finger and puts it in the hole, and on the other side is a guy with a hammer. He sticks his finger in and the guy hits his finger and he says OH CRAP! and puts his finger in his mouth.