Some info and a short description of this South Park episode on South Park Zone:
South Park - The Biggest Douche in the Universe is the 15th episode of the 6th season of the Comedy Central animated series South Park. It was first broadcast on November 27, 2002 and was the last in a mini-arc depicting Cartman being occasionally possessed by Kenny. The episode is centered around psychic John Edward, who the entire crew of South Park Studios agreed to be "the biggest douche in the universe."
Cartman is rushed to the hospital after again being possessed by Kenny, the first occurrence of which was in the episode "A Ladder to Heaven" when he mistook Kenny's ashes for chocolate milk mix. The doctor tells his mother Liane that Cartman is 'running out of time'. Upon hearing of all this, Chef decides to take everyone to the Crossing Over TV Show in New York and have John Edward talk to Kenny from beyond the grave.
Chef’s parents try to exorcise Kenny’s spirit from Cartman. Meanwhile, Stan calls out John Edward for providing false hope to people whose loved ones have died.
South Park Spoiler Alert!
(The complete plot for this South Park Episode)
Cartman is taken to the hospital for being possessed by Kenny's spirit for one full month.Cartman's mother is told by the doctor that Cartman is 'running out of time'. Upon hearing of all this, Chef decides to take everyone to the Crossing Over TV Show in New York and have John Edward talk to Kenny from beyond the grave. At the show, Edward merely makes uselessly vague statements about Kenny, and advises Kyle that his grandmother wants him to "look for four white doves".
Disappointed with Edward, Chef takes Cartman to his parents in Scotland and has them perform an exorcism. About to fly back to Colorado, Kyle spots a poster advertising a school called Jewleeard, with four white birds as its logo. Convinced, he rushes off to enroll himself. Stan goes to Edward's house, and offends him by trying to get him to admit that what he does is not real, and calls him a 'douche' and 'the biggest douche in the universe'. Before Stan leaves he steals some of Edward's books, to learn more about cold reading. In an attempt to persuade Kyle that Edward is a fake, Stan demonstrates cold reading on some passers-by as they stand in the street but backfires when the crowd believes that Stan actually has psychic powers, and he is immediately given his own show. This prompts Edward to challenge Stan to a psychic showdown.
Meanwhile, Chef's parents successfully exorcise Kenny's spirit from Cartman, but since Chef has not brought a "victim child" into which to transfer the spirit, it flies around their house before occupying a pot roast. Cartman returns to his normal self and Chef's parents give him the roast to take back to South Park. Chef's mother then touches Cartman and says "This child is clean!", a reference to the medium in the movie Poltergeist. However, Chef, Cartman, and Liane end up forgetting to claim the pot roast at the baggage claim in the airport.
At the psychic showdown, Stan finally convinces Kyle and much of the audience that, although it may be comforting to think of their deceased relatives talking to them, such a fate isn't a particularly desirable one- especially if it means that they have to talk to Edward. A large spacecraft suddenly crashes through the studio roof. The nomination committee for the annual "Biggest Douche in the Universe" award, made up of several different aliens, comes to take Edward to the award ceremony. Once taken there, Edward wins the prize despite throughout the entire episode yelling "I am not a douche!" — beating out a variety of aliens including one that is literally a giant douche.
Throughout the episode, fictional trailers play for Rob Schneider's latest comedy vehicles, The Stapler, A Carrot, and Da Derp Dee Derp Da Teetley Derpee Derpee Dumb. Near the end of the episode a trailer is shown wherein Schneider finds the abandoned pot roast and eats it, thus allowing Kenny's spirit to possess him. The resulting movie is titled Kenny and shows him living out Kenny's former life; at least until he is shot and impaled on a flag pole.