(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.

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.