The phrase comes from Bad, the title track of Michael Jackson's 1987 album, where the singer adopts a tougher streetwise persona and repeatedly asks who is bad. The song became one of his signature hits, and its hook lived on through radio, music videos and pop culture references. Online, the isolated vocal took on a second life as a short reaction clip, shared in edits and memes whenever someone wants to claim confidence or throw down a lighthearted challenge, keeping the moment instantly recognisable decades later.