A rabbi works for 30 years performing circumcisions all the while keeping the ""trimmings"" in a jar. When he retires he brings this enormous jar to the leather tanner's and asks the tanner to make him something out of it, ""anything!"" The leather tanner tells him to come back in a week. A week later the rabbi shows up, and the leather tanner slaps a wallet on the table. The rabbi is disappointed, ""after 30 years, all I get is a lousy wallet?"" ""But wait!"" exclaims the tanner, ""If you rub i…