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Dupa is the same as жопа in Russian. Kurwa on the other hand is dual use - it is used as an expletive (fuck!, блядь!) but also as a noun for a prostitute. In this case it's the combination that makes it so funny in Polish even if you don't really dig into meanings.
I mention UK because most people here are well accustomed with "kurwa!" as probably half of the personnel on building sites is Polish so you hear that a lot 😂