A doctor has been doing circumcisions for 30 years, and he's collected all the foreskins.
He has them all in a box, and decides he should do something with them. He takes them to a taxidermist and asks him to make something out of them.
A few weeks later, he returns to the taxidermist, who pulls out a small box and sets it on the counter. The doctor opens the box and there is a wallet. "I brought you all those foreskins, and all you could make is a wallet?"
"That's not just any wallet," says the taxidermist. "Rub it and it turns into a suitcase!"