Bruh started as informal slang for brother before becoming a standalone reaction word in online video culture, where its flat delivery made it ideal for short clips. The sound effect version spread through meme compilations, gaming videos, and short-form platforms, where creators reused it to mark moments of disbelief without needing any dialogue. Because it is instantly recognisable and only lasts a second or two, it has stayed in rotation long after many louder meme sounds faded, working across gaming, fails, sports, and everyday comedy.