Long time ago, God assigned a man to take a pair of all animals, a male and a female, to the moon. But there would be one condition: if any of the couples had sex with each other, the man would die; and he would become a king if the animals were brought to the moon and back without having sex. After thinking for a while, the man said he'd do it.
Hes grand plan: before they left, he told all the male animals that he was going to cut their penises, give them a receipt, and when they got back, they were free to take their stuff back. And so they did.
The trip to the moon was awesome. On the way back, the male rabbit asks the man, "Have we arrived yet?" "Patient," said the man. Later on, the rabbit asked again, "Are we there?" The man, looking at him strange, said, "It's a long way, please give it some more time." A bit later, the rabbit went to the man again and asked, "So, are we back on earth yet?" The man, getting angry, asked the rabbit, "What's hurry, rabbit?"
"Well," the rabbit said, "I got the donkey's receipt!"