Yiddish: You can't make a shtreimel out of a pig's tail.

SOURCE: Bernstein, Jüdische Sprichwörter und Redensarten.  A shtreimel is a fur-trimmed hat traditionally worn by rabbis and Hasidic Jews on the Sabbath and holidays.  And of course the pig is ritually unclean.  Compare:

.פֿון בלויז וואַסער קען מען קיין קרופּניק ניט קאָכן
Fun bloyz vaser ken men keyn krupnik nit kokhn.
You can't cook barley soup with just water.

SOURCE: Stutchkoff, Der Oytser fun der Yidisher Shprakh.

פֿון אַ חזירשן עק קען מען קיין שטרײַמל ניט מאַכן.

Fun a khazershn ek ken men keyn shtrayml nit makhn.

You can't make a shtreimel out of a pig's tail.