This clip belongs to the large family of short Brazilian Portuguese reaction sounds that circulate on short-form video and messaging apps, where a single spoken line does all the comic work. Sai fora is everyday slang for telling someone to go away, and the added hm gives it a sceptical, unimpressed edge that fits roasts, pranks, and fail videos. Because it is so brief and easy to understand even without translation, creators reuse it as a punchline, a cutaway, or a final word in edits, which keeps it circulating long after its first uploads.