If you said to someone “Je bent een pannenkoek!“, they’d probably have no idea what you were talking about, unless they spoke Dutch. This is a kind of mild / affectionate insult in Dutch meaning literally “You’re a pancake”.
It’s often used to refer to oneself – Oh, wat ben ik toch een pannenkoek! (Oh, what a pancake I am!) when you’ve done something stupid, dumb, foolish or clumsy.
Pannenkoek [ˈpɑnə(n)ˌkuk] means pancake, crêpe or flapjack. It comes from pan (pan, cooking pot) and koek (cake, cookie, biscuit, pie).
Pan comes from the Middle Dutch panne (pan), from the Old Dutch *panna (pan), from the Latin panna, a contraction of patina (a broad, shallow dish; a pan; stewpan; a kind of cake; a crib, manger), from the Ancient Greek πατάνη (patánē – a kind of flat dish) [source].
Koek comes from the Middle Dutch coeke (cake), from the Old Dutch *kuoko (cake), from the Proto-Germanic *kōkô (cake). The English words cake, cookie and quiche come from the same root – cake via Old Norse, cookie via Dutch, and quiche via French [source].
Words used in a similar way in Dutch include sufkop (“dull head”, numskull), dommerd (dummy), gekkie (weirdo, goof), oelewapper (ding-dong, dummy, monkey), druif (grape), oliebol (donut, dumpling), koekebakker (“cake bakker”), uilskuiken (“owlet”, nincompoop, birdbrain), flapdrol (fool, nincompoop), mafkees (weirdo, goofball), oen (“castrated donkey”, moron), sukkel (dummy, idiot, twerp) [Information from Anna Rutten and Wiktionary].
Some equivalents of pannenkoek I can think in English are muppet, idiot, wally, plonker and numpty. Others, from Reverso, include: knucklehead, slouch, douche and potato-head.
Can you think of more in English or other languages?