The line comes from The Simpsons and is spoken by Ralph Wiggum, the show's famously naive schoolboy, whose innocent delivery turned a simple warning into a lasting joke. Clips of the moment spread through online compilations and social media edits, where creators paired it with characters walking into obvious trouble. It later became a staple reaction sound in meme videos, because it instantly signals that someone has realised, too late, that they are in trouble.