We also have an actual german word for that, in addition to the phrases conveying similar meanings:

Egal.

Meaning something is irrelevant, does not matter, can be disregarded. So, something i give zero fucks about would be something that ist mir (scheiß)egal. Add swear words to your liking for emphasis.

Anyone who knows Japanese wanna weigh in?

I know maybe 3 dozen words in Japanese and the best I can do is “Nandemonaiya” which is something like “never mind” but could also maybe be used to say “forget about it”. Japanese is a super polite language though, so “it doesn’t matter” may be about as good as it gets? Also, Japanese tends to throw nouns out to mean a thing is like that noun, like you might call a homebody an “otaku” (house, as in they never leave it) (commonly used to refer to anime fans, as in they stay in all day watching anime) so maybe the word for “shit” or “garbage.” Shit, as in just saying the curse (like “dammit”) would be kuso (usually the vowels are silent, so it just sounds like “hiss” but with a K (but not “Kiss” if that makes any sense). But “kuso” is more like “dammit,” like I said, I wouldn’t use it to say I don’t care, more that I’m annoyed and bothered.

“zero fucks given” means “I don’t care” but is a) profane and b) carries extra connotations. “das ist mir wurst” isn’t crude in the same way at all, and I don’t think it carries the same implication of keeping cool.

Translating idioms is hard and they rarely translate exactly, but especially if you pick an idiom which is already a niche way of saying something that there are more common ways to express.

The Spanish one is primarily from Spain. You hardly hear it used in latin America, but it is still well understood. How the venerable cucumber became synonymous with “worthless”, I do not know.

My Spanish speaking friends and family use “…no me importa un carajo” which is close to “…do not care a fuck”, which is the same vibe as “don’t give a fuck”. The word “carajo” is very flexible, like fuck, as is “cabrón” which technically means cuck but is often used in many ways both negative and positive, depending on context.

Italian:

• I don’t care a d*ck
• I don’t care a dried fig
• I don’t care a cabbage

Danish: it concerns me [to the extent of(?)] a cardboard-duck / harvest-flower

(Det rager mig en papand / høstblomst)

Ah, we have reached another cycle of reposting this. Good to have, since I don’t use a calendar and would otherwise not know which year we have. /j

(Note, I am not against reposts if spaced “far enough” in time, because as mentioned before: I don’t use a calendar. /j)