The line comes from Dragon Ball Z, where Vegeta uses a scouter to measure Goku's fighting power during their first major confrontation on Earth. When the reading climbs past 9000, his disbelief turns into the now-famous scream, and the scene was later shared widely as a short clip online. Its exaggerated delivery made it easy to reuse for any moment that felt impossibly large, and it became one of the anime fandom's most recognisable reaction sounds. It still works because the number itself has become shorthand for going completely over the top.