I recently learned "Arschgeige" in German, which according to the reactions of people I asked, is a pretty mean thing to say. I can't get over the fact it literally means butt violin though.
It is fiddle as in a violin type instrument. The sheer absurdity makes me not be able to take this insult seriously at all. I don't get how anyone does, but it's apparently a really shitty thing to say to someone. You ass violin!!! lmfao