A llama, a penguin and a donkey are captured by the king. Whoever doesn't manage to make him laugh is going to be shot.
The llama is first. It tells jokes for hours, but doesn't get the king to laugh. Thereupon it is shot.
The penguin is next. He also runs with telling jokes, but he doesn't succeed, thus he is shot.
The donkey is next. As soon as he starts telling, the king bursts out in laughter.
The donkey is confused: "I haven't even finished my joke yet!"
The king: "I just figured out the penguin's joke!"