A little fella called Keith walks into a bar. Unfortunately, there is a pile of dog dung just inside the door, and he slips in it and falls over.
He gets up, cleans himself up and walks to the bar and buys a drink.
A great big man called Pete then enters the bar. He too slips in the same pile of dung, falls over, gets up, cleans up and then goes and buys a drink.
The little Keith turns to Big Pete and, trying to strike up a conversation, points to the pile by the door and says, "I just did that."
So, Big Pete punches Keith in the mouth.
Took me a second but then I laughed.