Jared Fogle, the ubiquitous spokesman for Subway, visits South Park, touting that, "Weight loss is easy" with a regimen of sub sandwiches. When Stan, Cartman, Butters, and Kyle visit Jared after his speech to the town, they are dismayed to find that his amazing weight loss is the result not of eating all the sandwiches he wanted, but of intensive consultations with a personal trainer and a dietitian (who he refers to as his "aides"). Cartman suggests that the boys cut a similar deal with the local Chinese restaurant, City Wok, and that Butters should gain 50 pounds and then lose it, claiming that his weight loss was due to a strict diet of City Wok.
Meanwhile, after being confronted by the boys, Jared decides to tell the world his secret to weight loss. He informs his girlfriend Christine that he has had help from "aides", causing her to believe that he has Acquired Immunodeficiency Syndrome and sparking a running gag in which everyone mistakes the word "aides" for the disease AIDS for the rest of the show. He also comes clean with the people of South Park, suggesting that everyone who wants to lose weight should get aides. For this, Subway decides to fire Jared from his promotional duties.
The boys cut a deal with City Wok's stereotypical proprietor, Tuong Lu Kim, and the next phase of the plan begins. They have Chef help them fatten up Butters and have Cartman put him on an exercise regimen. Unfortunately, Butters does not lose weight from exercise. The only remaining option is liposuction, which involves a hose and pushing Butters' stomach, to remove the fat from Butters' body. However, after the procedure, Butters' parents come home, and Cartman, Stan, and Kyle manage to leave before they enter the house. Butters' parents immediately ground him despite him laying on a table with an open wound, thinking he had self-performed liposuction surgery in the house after they had warned him four times to never do so.
Jared surmises that the reason for this turn of events is that others cannot afford to hire their own aides to assist in their weight loss. Thus, Jared devotes his money to the Aides for Everyone Foundation, dedicated to providing aides to everyone, including personally giving aides to every underprivileged child in the world. This does not go over too well with the townspeople, and Jared is chased through town by an angry mob. When he escapes, he vents his frustrations by (literally) beating a dead horse (the literary "Dead Horse" being the running "Aides/AIDS" joke).
Stan and Kyle sneak Butters out of his house (with Cartman covering for him) and take him to City Wok, but the owner decides that he wants nothing to do with his "very own Jared" due to recent events. The boys run downtown to intercept the mob, but Jared is already at the gallows. Back at the Stotch residence, however, Cartman masquerades as Butters on the phone when Mr. Stotch calls home. When Mr. Stotch asks if he is watching TV, Cartman claims that he was just "jackin' his hot spicy boner" and proceeds to call him a "bloody vaginal belch". After telling Mr. Stotch "Bring it on, queerbait," Cartman hangs up on Butters' father and laughs. Mrs. Stotch calls shortly after, telling him how upset her husband was. Cartman uses more trash talk on her before hanging up on her, saying, "I'll be waiting with bells on, you old horse banging skank." Meanwhile, Stan and Kyle manage to stop the lynching by clarifying the running gag to Jared, the Subway executives, and the townspeople. Everyone determines that AIDS is finally funny, since it has been 22.3 years, and a monument is unveiled declaring it as such.
Now that Jared has returned to favor, the City Wok owner offers the boys $15 to use Butters in his advertising, which is rejected. Butters then runs home and thanks Cartman for covering for him, calling him a true friend. Cartman thanks Butters, then as soon as he gets outside, Cartman pulls up a deckchair, theater popcorn and a soda outside of the house and happily listens as Butters' parents return home and beat him for what they believe to be his earlier manner on the phone.