Yiddish is not my native language but I think this one is so good it absolutely deserves a mention:

All of your teeth shall fall out except one that gives you a massive toothache.

“Κλάσε μου τα αρχίδια” which literally stands for “fart my balls” in Greek.

It’s a way of telling someone to go fuck himself.

My personal favourites from Finnish.

“Ei ole kaikki muumit Muumilaaksossa” “Not having all the Moomins in Moomin Valley” Used for people who are either stupid or lack sanity. There are other variants of this and Moomin one is not older than a couple of decades.

I find our version of Grammar Nazi pretty great. We call them comma fuckers.

“Ei voi kauhalla ottaa jos on lusikalla annettu” “You can’t take with a ladle if it was given with a spoon”. This refers also to a lack of something, usually a lack of intelligence or sense.

Dich haben sie bei der Geburt drei Mal hochgeworfen und zwei Mal aufgefangen.

When you were born, they threw you three times and only caught you twice.

In Argentina, “Boludo” or “Pelotudo”. It’s very common to hear both, but the first one is like a little bit friendly, you can use it with friends and they’ll accept it, but in the other face, “Pelotudo” isn’t that friendly and it is regularly used to just insult, haven’t found anyone that used that ironically.

“Spargeltarzan”, which is German for “asparagus Tarzan”. Basically someone who is physically weak, but tall and lanky.

I also like “Lauch”, which just translates to “leek”, the veggie. Oh, and “Bohnenstange”, which means bean stalk. We do seem to have quite a few vegetable-related insults in German, now that I think of it…

Du hast doch nicht alle Tassen im Schrank - German, you don’t have all your cups in the drawer.

Telling someone he is stupid via comparison to cups. Why? Who knows.

If you want to say that you don’t care about something (as in: “I don’t give a fuck”), in Serbian you would say: “My dick hurts”. And that’s an expression you’ll hear almost daily. A less used variant of that, but still legit is: “My balls are beeping”.

While not insulting, I’ll throw in our way to say: “I’m/You’re fucked”. It’s: “Jebao sam/si ježa u leđa”, which means: “I/You fucked a hedgehog in the back”

In Quebec French, people sometimes say of someone who’s not particularly bright:

“His mom rocked him/her too close to the wall.”

It’s just so… vivid and random.

German: “Dich soll der Blitz beim Scheißen treffen” - Lightning shall strike you while you’re taking a shit

Best insult ever, imo.

Let’s throw some west-southern german things in here!

Seggl: Just a general insult to someone but not too bad. On the level of ‘idiot’

Schafseggl: Just seggl with the prefix sheep. Slightly more derogatory

Grasdaggel: grass-dachshund, same level as Schafseggl

Word: Muji

In Devnagari (Nepali): मुजी

Meaning: A woman’s pubic hair

In sentence: तँ मुजीको गाला फुट्नेगरी पड्काउॅछु।

Translation: I’ll slap the living crap out of you muji.

Here are a few Austrian ones:

“Häferl” (Cup): someone with anger management issues

“Du rüttelst am Watschenbaum” (You are shaking the slap tree): I’m close to deliver the fruit of said tree to you.

“Ohrwaschlkaktus” (Ear cactus): Someone with large, protruding ears

“Saubauch” (Hog belly): A way of telling someone that they are fat and dumb at the same time. But in a nice way.

Not my native language but the German language has some pretty fantastic words/insults like “punchable face” (backpfeifengesicht) and “brain denier” (gehirnverweigerer).