Who is Froyker-Sheygatz, Efrayim Katz from Tevye the Dairyman and the Railroad Stories and what is their importance?

Froyker is an orthodox Jew, but known for taking certain liberties and being a bit wild. He is raising funds for a charity for a burnt-down village. He wants Tashker to give money, so organizes a trick where Tashker bets that Mr. Kompanyevitch is not wearing a Tallis Koton.