Obviously German has a shit-ton of words and expressions that English doesn’t because of its affinity for compounding. So I collected my faves!
das Luftschloss lit. sky castle an unrealistic dream
die Eselsbrücke lit. donkey bridge a mnemonic device
der Erbsenzähler lit. pea counter a control freak, someone who needs to count peas
der Pantoffelheld lit. slipper hero someone who is “whipped” or can’t stand up to their significant other
der Kummerspeck lit. worry bacon the weight you put on when you overeat due to worry or stress
der Treppenwitz lit. stairs joke the clever joke you only think of after you’ve left the relevant situation and have already started down the stairs
der Dreikäsehoch lit. three cheese high someone who is very short, i.e. as tall as three cheeses stacked on top of one another
der/das Kuddelmuddel lit. mishmash? chaos or mess
der Weltschmerz lit. world pain the feeling that comes from living in a world that isn’t perfect
verschlimmbessern lit. to make worse better to make something worse while trying to make it better
das Arschgeweih lit. ass antlers tramp stamp
die Arschgeige lit. ass violin someone who can’t do anything right
die Waldeinsamkeit lit. forest isolation the feeling you get when you are alone in the woods, truly communing with nature