Yiddish: He's an expert like a goat's a connoisseur of music.

SOURCE: Stutchkoff, Der Oytser fun der Yidisher Shprakh.  Literal translation:  He's an expert like a goat's an expert on a musician.  The Yiddish word klezmer refers to the musician, not the music.  Variations:

Er iz a meyvn vi a khazer af heyvn. | .ער איז אַ מבֿין ווי אַ חזיר אויף הייוון
He's an expert like a pig's an expert on yeast.

SOURCE: Bernstein, Jüdische Sprichwörter und Redensarten

Er iz a meyvn vi a kats af heyvn. | .ער איז אַ מבֿין ווי אַ קאַץ אויף הייוון
He's an expert like a cat's an expert on yeast.

SOURCE: Stutchkoff, Der Oytser fun der Yidisher Shprakh

ער איז אַ מבֿין װי אַ באָק אױף אַ כּלי–זמר.

Er iz a meyvn vi a bok af a klezmer.

He's an expert like a goat's a connoisseur of music.