Sustaço comes from the Portuguese word susto, meaning a scare or fright, with an augmentative ending that implies something much bigger and more dramatic. The clip circulates online as a short reaction sound rather than as a known scene from a film or show, so its popularity comes from how easily it fits short videos. Brazilian creators and editors use it for pranks, jump scare jokes, and exaggerated reactions, and its three second length makes it easy to loop, layer, or drop into a soundboard collection.