An angry bartender was closing up for the night when he heard a knock at the door. He opened the door, didn't see anybody, and was about to close the door when a voice called, "Hey, down here."
The bartender looked down and saw a snail.
"Hey," the snail asked, "How about a drink?"
The angry bartender snarled, "First of all, we're closed. Secondly, we don't serve snails."
And with that, the bartender kicked the snail all the way across the street.
A month later, the same angry bartender was closing up for the night when there was a knock at the door. He opened the door, and there was the same snail from last month.
"You know," the snail said, "you didn't have to kick me."