Looking for a joke, who doesn't laugh when diving.

One day, pigs, monkeys, turtles and rabbits gathered around to tell jokes, and it was agreed that whoever told jokes would be thrown into the river as long as he didn't laugh. First, monkeys. After he finished, everyone laughed, except the tortoise. Everyone threw him into the river. Then piggy, when he finished, everyone laughed, except the tortoise. Everyone threw the pig into the river again. It was the tortoise's turn. He laughed: "The joke told by the monkey just now was really funny!" " "