I'm a non-Italian speaker, seeking contextually-appropriate expressions for shocked surprise, even better would be seriously shocked/scared surprise. (This is for a novel.) A literal translation of, "Oh, shit!" is doable, but is that colloquial or simply not what an Italian speaker would say? Is such a question OK here, or close-bait?
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I think this would be an acceptable question: it's about Italian usage, after all, and not simply a translation.
Maybe it would be better to try and make it more general.
I suggest to add a description of the situations in which the character happens to be shocked or surprised: the context is important for finding the right words and this would perhaps make for increased generality.