Get dunked on comes from basketball slang, where being dunked over is treated as the ultimate on-court embarrassment, and the phrase moved naturally into online trash talk. As short reaction clips became a staple of gaming videos, sports compilations and social media edits, the taunt became shorthand for any moment when someone is beaten in spectacular fashion, not just on a court. Its staying power comes from that simplicity: everyone understands instantly that the person being mocked has been shown up, which makes it endlessly reusable for fails, rivalries and comeback clips.