A man walks into a bar and sits on a stool. In front of him, he sees a large jar full of money and a small card that reads: "If you'd like to win all this money, you must make the horse at the end of the bar laugh. Cost: $5."
He pays five dollars and leads the horse into the bathroom. Two minutes later, they emerge. The horse is laughing so hard it urinates on the floor. The man takes the money and leaves.
The next day, the same man returns to the bar. He sees the horse and the jar again, but this time the card reads: "You can win all this if you make the horse cry. Cost: $10."
He pays ten dollars and takes the horse into the bathroom. Four minutes later, they come out. The horse is crying as if heartbroken. As the man takes the jar, the bartender stops him and asks, "How did you do that?"
The man replies, "The first time, I told him mine was bigger than his. The second time, I showed him!"