In 2007, Parker called Season Five "the one where shit starts getting good",[2] and Stone said "Season Five is the best one."[3]
The penultimate episode of the season, "Kenny Dies", sees Kenny's "permanent" death from a terminal disease. Up until this episode, Kenny would be killed in (almost) every episode as a running gag. According to Matt Stone and Trey Parker, they were running out of ideas for creative ways to kill Kenny and in general had grown tired of his character, not seeing a point to keep him around.
Season 6 focused on the other boys coping with Kenny's death and trying to find a replacement (first Butters, then Tweek). Due to outcry from fans, he was eventually written back into the series at the end of the season 6 finale.
When a crime drama on TV airs an episode using the curse word shit uncensored, the town popularizes the word, which causes people to die from the plague and the boys, with assistance from Chef, attempts to break the chanting chatter of the word.
A David Blaine cult comes to South Park, but soon has brainwashed the boys, except for Stan, leading him to get the "Super Best Friends" into saving the world and into trying to destroy Blaine.
When Cartman is conned by Scott Tenorman, who convinced Cartman that buying pubic hair will make him reach puberty, he bursts out his anger into getting his revenge on Scott as soon as possible.
The school is forced to teach sex education to the students at a younger age after the boys are found giving dogs handjobs, leading to a gender war because of incompetent teaching methods.
In order to get their video game console back, the boys must bring a drug-smoking towel to the government from the feud between paramilitaries and extraterrestrials.
Cartman "blows a funny fuse" when his prank of putting Kenny's butt on a milk carton prompts a family with butts for faces to come to South Park in search of their long lost son. Meanwhile, Butters gets grounded for his supposedly bad school photo.
Kyle's cousin, a stereotypical nebbishy Jewish boy also named Kyle, comes to stay with him for weeks. Meanwhile, Mr. Garrison's anger towards airline service after the September 11th attacks prompts him to create a new version for transportation.
Kenny contracts a severe muscular disease and he is placed in a hospital, where he spends his final moments with his best friends before he dies "permanently". Meanwhile, Cartman is selling aborted fetuses from a crashed truck.
When Butters survives a murder attempt by his mother after discovering a shocking secret about his father, he must travel back to South Park in time for his parents' wedding anniversary at Bennigan's. Meanwhile, Butters' parents join Gary Condit, O. J. Simpson, and the Ramseys in lying to the press about who murdered Butters.