The line comes from Dragon Ball Z, where Vegeta, scanning Goku with his scouter, is stunned to find his rival's power level far beyond what he expected. In the English dub the reading is given as over 9000, and the moment was clipped, remixed and captioned across early video sites and forums. It became shorthand for anything unexpectedly huge, from scores and follower counts to prices, and its exaggerated delivery has kept it in constant use in memes, reaction videos and gaming edits ever since.