Bruh began as informal slang for brother before becoming a staple reaction word in online humour, where a single drawn-out utterance could sum up disbelief without any explanation. Short video platforms and meme pages adopted the sound because it is instantly understood across different clips, from gaming fails to everyday embarrassments, and its brevity makes it easy to reuse as a punchline. It remains popular because the tone carries the joke on its own, needing no context beyond the moment that prompted it.