The line comes from South Park, the animated series created by Trey Parker and Matt Stone that first aired in 1997. In the early seasons, Kenny McCormick died in almost every episode, usually in a sudden and gruesome way, and Stan would shout in horror while Kyle followed with an angry response. The gag became one of the show's most recognisable running jokes and spread through clips, memes and soundboards long after Kenny stopped dying so often. It survives because the phrase instantly signals a sudden, absurd death.