Guy goes to a doctor because he wants to have the foreskin removed from his dick.
The doctor tells the dude this is not a problem, and eases the guy's mind by telling him that he has many patients who have had the procedure done.
On the counter in the examination room is a jar full of what looks like clumps of skin.
Curious, the dude asks the doctor what's in the jar.
The doctor tells the guy that he keeps the foreskins of his patients, and his wife makes wallets out of them.
The guy is even more curious now, and asks the doctor what is so special about a wallet made from dick skins.
The doctor replied that when you rub the wallet it turns into a suitcase.