A guy walks into a bar carrying an 18" alligator.
The bartender says, "What do think you're doing? Get that goddamn thing out of here. I don't allow pets in my establishment".
The guy tries to explain. "Look he won't cause any trouble. He's well trained and I'll prove it". He then proceeds to put the alligator on the bar and says, "open".
The alligator open its mouth and you can see all of its razor sharp teeth. "Now watch this", he says and proceeds to remove his penis through his zipper and lays his balls gently onto the alligator's teeth.
He then orders a beer and proceeds to drink it. All the while the alligator keeps its mouth open and nothing happens. After finishing the beer the man gently removes his penis and puts it back into his pants.
He then says, "close" and the alligator closes its mouth. "You see he is perfectly trained. He would do that for anybody. Does anyone want to try?"
After looking around he finally here a drunk whose sitting at table say "Sure I'd like to try. But I don't know if I can keep my mouth open that long."