Following 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's depression is mistakenly diagnosed as Asperger syndrome because he received a flu vaccination a year earlier. Taken to an Asperger's Group Therapy Center, Stan is greeted by a doctor who introduces him to the other patients, all exhibiting an assortment of odd behaviors.
When left alone, however, all the people quickly drop their act, and the false doctor reveals that not only do none of those present have the condition, they do not even believe that it exists. Stan learns that the center is actually a front for cynical self-perceived freedom fighters who believe that the world really has turned into feces, and that some kind of supernatural force is preventing the rest of the world from noticing. The leader, who is a parody of Morpheus from The Matrix, gives Stan a glass of Jameson Irish Whiskey as a "serum" so he can interact with the "illusion world", and charges him with convincing others to see the world as they do.
As this occurs, Cartman, upon mishearing the condition as Ass burgers, attempts to fake this condition at school by stuffing his underwear with hamburgers. Although this fails, Cartman gives one of the hamburgers to Kyle, who declares them delicious without knowing that Cartman had them in his underwear. This inspires Cartman to start a food stand with Kyle called Cartman Burger, at which he will sell hamburgers that he has placed between his buttocks. While intoxicated, Stan unsuccessfully attempts to make amends with Kyle, who explains that things have irreversibly changed and he must remain with Cartman Burger. The next day, Stan 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. The representatives deduce that Cartman Burgers contain ingredients from all of their products, which are infused into Cartman Burgers via some type of gas. When Stan arrives and loses consciousness from the alcohol, the restaurant agents tie him up and interrogate him about the secret ingredient.
As Stan does not know the ingredient, the representatives subsequently monitor a conversation between him and Kyle over the ingredient, but when Kyle tells Stan that only Cartman knows the secret ingredient, the restaurant agents storm the stand before the severely drunk freedom fighters arrive and gun them down. Stan, however, refuses to drink any more whiskey, 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, Randy Marshappears and announces that he and Sharon Marsh have worked out their differences and are reconciling. This surprises and upsets Stan, and he relapses into depression as, in a montage, everything returns to normal. The Marshes move back into their home together, and Kyle breaks off his friendship with Cartman and shuts down Cartman Burger after finding out just exactly what the secret ingredient is.
After Stan wakes up on a subsequent morning, Kyle, Cartman and Kenny appear in his bedroom and invite him to the movies with them. Resigned to his fate, Stan reluctantly joins them, taking a swig of whiskey on his way out.