A rabbi is planning on retiring from his main occupation, which is giving circumcisions. Over the years he's saved up all the foreskins from all the circumcisions he's taken part in. He looks at them and decides to take them to the local leatherworker to see if something can be made of them.
The rabbi explains that he'd like to have a retirement gift made out of the foreskins and the leatherworker agrees and tells the rabbi to come back in a couple weeks.
A couple weeks later the rabbi comes back and the leatherworker hands him a wallet.
"All those foreskins and you only made me a wallet?!?" The rabbi exclaims.
The leatherworker replies, "Don't fret, if you rub it a bit it becomes a suitcase."