"Ass Burgers" is the eighth episode of Season Fifteen, and the 217th overall episode of South Park. It aired on October 5, 2011. It continues and concludes the story started in "You're Getting Old".
Cartman tries to give himself Asperger's Syndrome in an odd way. Meanwhile, Stan can't seem to get his life back to normal no matter what he tries. Will anything ever be the same in South Park again?
Continuing the events of "You're Getting Old", Stan is attempting to adapt to his parents' divorce while his cynicism causes him to explode in class out of frustration. Stan is mistakenly diagnosed with Asperger's Syndrome because he received a flu vaccination a year earlier. Taken to the Asperger's Research Center, Stan learns that it is front for cynical self-anointed freedom fighters, called the Secret Society of Cynics, who believe the world really has literally turned into feces and that some kind of supernatural force is preventing the rest of the world from noticing. They do not actually know who this enemy is; and speculate that it could be aliens, robots from the future or mutants. The leader along with his patients, who are a parody of Morpheus and other characters from The Matrix films, gives Stan a glass of Jameson Irish Whiskey as a "serum" so he can interact with the "illusion world." As this occurs, Cartman, upon learning that there is a condition called "Asperger's" (which he mistakenly hears as "Ass Burgers"), attempts to fake this illness at school by stuffing his underwear with hamburgers. Although this fails, Cartman gives one of the hamburgers to Kyle and another student, who declare them delicious without knowing that Cartman had them in his underwear. This inspires Cartman to start a food stand, so he can sell his hamburgers that he has farted on. While drunk, Stan attempts to make amends with Kyle, but he is unsuccessful.
The next day, Stan returns to the Asperger's center and is once again plied with whiskey. This time, he is sent armed to a secret meeting being attended by corporate representatives of America's most popular fast food chains, which have lost business due to the popularity of Cartman Burger which they theorize to that the ingredients from all of their products are converted into a gas that is then infused into the food. When Stan arrives and loses consciousness from the alcohol, the restaurant agents tie him up and interrogate him out of believing that he is sent by Cartman Burgers. But recognizing him as Kyle's friend, the fast food chain corporates hold Stan at sniper point while subsequently monitor a conversation between him and Kyle over the secret ingredient. But when Kyle tells Stan that only Cartman knows the secret ingredient, the restaurant agents storm the stand before the Asperger's freedom fighters arrive to gun them down. Stan, however, refuses to drink any more Jameson, and realizes that although he may no longer be with both of his parents and Kyle is no longer his best friend, he is now excited by the prospect of change rather than scared of it, claiming this could be the start of new, original adventures for everybody.
However, Stan's father Randy pulls up in a van and announces that he and Sharon have worked out their differences and are getting back together. Sharon then explains to Stan that sometimes people need to stick to what they know, even if it means remaining unhappy, which upsets Stan, as it contradicts his epiphany. In the montage, the Marshes move back into their home together while Kyle breaks off his friendship with Cartman after learning the secret ingredient and exposing Cartman's farting on the hamburgers to the public, and Stan out on a picnic together with Wendy, looking disinterested throughout. After Stan wakes up on a subsequent morning, Kyle, Cartman, and Kenny invite him to the movies with them. Resigned to his fate, Stan half-heartedly joins them, but not before taking a swig of whiskey on his way out.