A surgeon retires from his long career as a specialist in circumcision. Throughtout his career he has saved hundreds of foreskins as mementos and now wishes to turn them into a souvenir. He takes his specimens to a leathersmith and asks him to make something out of them. A week later the surgeon returns and the leathersmith presents him with a wallet. "All those foreskins and you only made me a wallet?!" exclaims the surgeon. The leathersmith replies, "Yes, but if you stroke it, it becomes a briefcase."