The line comes from Dragon Ball Z, where Vegeta uses a scouter to measure Goku's power level during their first confrontation and is stunned to find it has risen above 9000. The moment was clipped, remixed and captioned across early video sites and forums, becoming one of the first anime lines to break into mainstream internet meme culture. Its staying power comes from its flexibility: any unexpectedly large number can be framed as a power level, making the shout a shorthand for shock at scale that still lands in gaming, reaction and parody edits today.