It's also definitely a ‘minced oath’ for ‘похуй’—which involves the dick and a prefix/preposition that is basically random, as usual for abstract idiomatic expr

It's also definitely a ‘minced oath’ for ‘похуй’—which involves the dick and a prefix/preposition that is basically random, as usual for abstract idiomatic expressions in various languages. For general absence of fucks, there's also the suitable ‘it doesn't fuck me’.