A guy was watching a camel caravan preparing to leave the oasis for a long journey through the desert.

He had often wondered how the camels survived these journeys without needing water for many days.

So, he approached the camel herder who was taking a camel down to the edge of the oasis to drink to ask him the the question.

Well Effendi, says the camel herder, as the camel is drinking you use two bricks, one in each hand, and clap them together on the camel's testicles.

The camel takes a sharp intake of breath, and at the same time gallons of extra water, this sustains the camel for many days.

Oh I see says the guy, very clever, but does it hurt?

Only if you trap your thumbs between the bricks, says the camel herder.