Short question clips like this spread on soundboards because the line works without any context, and Who Are These Ninjas became a shareable reaction for moments built around sudden stealth characters. The phrasing is plain and instantly quotable, so creators reuse it in gaming edits, costume reveals, and meme compilations where a group appears out of nowhere. Its popularity is less about a single viral post and more about repeat use, as the same confused question fits a new scene every time ninjas show up unexpectedly.