They were riding the camel through the desert and the camel would not drink.
After five days, they found an oasis, and tried to make the camel drink, but he wouldn't.
So after a while of the camel not drinking, the animal-husbandry guy said to his friend, "Hold his head under water, and I'll suck from his hind-end and make him drink.
In two minutes, the guy in the rear said "you got his head to deep, I'm sucking mud!"