Kenny Dies

"Kenny Dies" is episode #513 of South Park.

Plot
The episode begins in an abortion clinic. A woman is giving her permission for scientists to use her dead fetus for stem cell research. However, an accident destroys the truck which was carrying all the fetuses from the clinic to the research facility. Cartman happens to be passing by at this moment, and he notices the cargo of the truck. He then steals the fetuses, hoping that he'll be able to resell the fetuses and get a huge profit off of them. He gets distraught, though, when the government makes stem cell research illegal immediately after that.

Meanwhile, the boys find out that Kenny has been diagnosed with a terminal disease, known as muscular dystrophy. Everyone is shocked by the news, (surprisingly, since he's dies in nearly every episode before that) and everyone except Stan tries their best for Kenny. Stan, however, is too upset to be near Kenny in his state, and refuses to even visit him.

Cartman wants to restore stem cell research, and a researcher explains to Cartman about how the studies actually work. With this information, Cartman realizes that the SCR might also be used to help Kenny recover from his illness. He then thinks that the research could also be used to duplicate a "Shakey's Pizza". The researcher recommends using lumber for that second idea.

Then Cartman gives a very thoughtful speech to the House of Representatives, requesting that the SCR ban be lifted, explaining about his best friend, Kenny, who's slowly dying as they speak. He then says that he believes the research can save Kenny's life. The House of Representatives committee then lifts the ban after Cartman sings "Heat of the Moment". Cartman begins visiting abortion clinics throughout the area, in order to collect even more aborted fetuses.

Meanwhile, after Chef gives Stan a little lecture on death, and why God lets it happen at any given time, Stan finally decides to visit Kenny. Kyle, however, explains that Kenny has already passed away. Stan calls himself Kenny's worst friend after Kyle mentions that Kenny's final words were, "Where's Stan?", and he goes back into his depressed state.

As the funeral takes place, Cartman comes rushing in and drags Stan and Kyle out of the ceremony, explaining that they have to see the "miracle" that's just occurred. The boys are horrified to see that, instead of using the stem cells to save Kenny, Cartman manipulated them into duplicating a Shakey's Pizza. As Kyle beats Cartman up for supposedly betraying Kenny, Stan says "I wasn't Kenny's worst friend! Cartman was!"

Trivia

 * This episode marks the only known time when Kenny's death was taken seriously by the main characters. With all of his deaths before that, the others would merely express surprise, then forget about it.
 * This episode had been initially intended to kill Kenny off for good because Trey and Matt grew tired of killing him off in every episode for the sake of humor. In addition, Kenny's repeated deaths made it tough to develop Kenny's personality, since he was really just a "prop" character. Kenny's subsequent absence from season six also allowed minor character Butters Stotch to rise as a major character on the show.