By the way, The German words in Yiddish are not bastardized standard German, but bastardized Pfälzisch, basically the dialect where I grew up. "Gefilde Fis[c]h" is how one would pronounce "Gefüllter Fisch" there, etc.

In the middle ages, the Mainz-Worms-Speyer region was the center of Jewish life in Germany.

I think I even found a wrong explanation on that Wikipedia page, simply by knowing Pfälzisch: A "Schnook" is a housefly. It doesn't match the Yiddish meaning that well, but it's the exact same word.

(The above second comment is also edit-locked, but at least at the moment this one isn't, even an hour-plus later, so evidently it wasn't "landīca" that triggered the logic, despite being by far the most offensive term in the whole comment.)

My wife, a native speaker of Spanish who doesn't speak German, reports that to her ears German sounds angry rather than silly.