Cartman runs a 'pest control' service to try and rid the town of hippies, people he feared and hated for most of the series, mainly because "they smoke pot, wear crap and smell bad." Having studied hippies in his quest to eradicate them, Cartman deduces that the hippies are about to start a music festival in South Park. His attempts to warn the town council are futile, and he is arrested soon afterwards for imprisoning 63 captured hippies in his basement.
The town of South Park is soon invaded by the largest population of hippies in the history of man, and the music festival threatens to destroy the town. They manage to convert Stan, Kyle and Kenny to their cause with talks of corporate evils, and the trio get caught up in the massive hippie crowd where they all listen to jam band music.
Cartman pleads with the mayor to stop the festival, but it turns out that the mayor was the one who permitted the music festival in the first place. But after seeing the chaos that the eccentric hippies are creating, the mayor is ridden with guilt and shoots herself in the head (she survives and appears later in the strategy room when Cartman is enacting his plan). The rest of the town then pleads with Cartman to rid the town of the hippies. Cartman eventually agrees to help, but only after Randy promises to offer a Tonka radio controlled bulldozer, as well as Kyle's mother assuring that Kyle would never have one, and instead have to watch Cartman having fun with the bulldozer.
Meanwhile, Stan, Kyle and Kenny realize that the hippies are doing nothing to oppose the corporations that they have demonized and that their idea of a perfect society is the same as the currently existing one. They try to leave but the crowd is 7 miles in radius and Stan's efforts to talk sense into the hippies only make matters worse. Cartman, with the help of a scientist, an engineer and a "black man to sacrifice himself in case anything goes wrong", builds a giant drill ("Hippie Digger") to bore through the hippie crowd, killing them all. Cartman then uploads a Slayer CD (hippies apparantly hate death metal.) The plan works and the hippies disperse, saving South Park. Stan sees Randy and they end up hugging each other, knowing that they're safe. Cartman then pulls out a knife and tells Kyle that he will never be a hippie again and that he has plans for him. Kyle is then forced to watch Cartman having fun with his Tonka bulldozer in the school parking lot.