After seeing 38-year-old Carlos Lopes in the 1984 Summer Olympics on TV, Homer decides to participate in the Springfield marathon to prove to Marge that he is fit. In the end though, Bart comes out as a surprise winner, by entering from a side alley near the end, wearing a stereotypical Italian costume as a disguise. Unfortunately, while receiving the trophy, a bird rips off Bart's fake moustache, causing an angry mob to chase after him. Cornered, he accepts a ride from a stranger to escape. The stranger introduces himself as 'L.T. Smash', who happens to be a music producer. Smash offers Bart a career as a member of a boyband known as "The Party Posse", as his stunt showed he has the right bad boy attitude. Bart accepts, and becomes the Party Posse's fourth member, joining Nelson, Ralph and Milhouse. The Party Posse quickly ascend to stardom, albeit using complex voice enhancers built by NASA. They perform at Springfield Elementary to high applause.
The band releases a single video (directed by Ang Lee), titled "Drop Da Bomb", which contains the chorus, 'Yvan eht Nioj'. Lisa's growing suspicion around The Party Posse eventually results in her discovering the line is a subliminal recruiting message to join the Navy, as 'Yvan eht Nioj' is 'Join the Navy' written backwards. In addition, while freeze-framing the video Lisa discovers that a recruiting poster featuring Uncle Sam was included in the video for a split second. Lisa sees that Otto has decided to join the Navy, and so goes to find L.T. Smash, where she discovers that he is actually Lieutenant L.T. Smash. He says he is working to recruit people for the United States Navy, and that bands have often been used for recruiting. Lisa points out her discoveries to Homer and Marge, but they dismiss her accusations as jealousy of Bart. The events come to a head when The Party Posse perform at a concert on an aircraft carrier, which only increases Lisa's suspicion towards the band. During the first song (which also contains subliminal messages), Smash learns from his superior officer that Mad Magazine's next issue will lampoon The Party Posse, calling them 'The Potty Posse', and thus the band will no longer have any recruiting power. Smash's superior officer also explains the new administration is having 'Project Boy Band' shut down and turns off the band's voice enhancer, exposing the group's mediocre singing voices, and causing the concert to fail.
Aggravated by his superior officer's actions, Smash goes insane and threatens to send the carrier out to sea. When Smash completes his threat, a terrified audience leaves the carrier. Smash sails the ship to New York City in an attempt to destroy Mad Magazine Headquarters. Despite the attempts of boyband 'N Sync to stop Smash, he destroys the Mad Headquarters with the ship's missiles, although the Mad workers manage to survive. After Smash's criminal actions, he is arrested and the potential of the fraudulent Party Posse remains unfulfilled. However, the Posse is upset they did not appear on the cover of Mad.
The episode ends with 'N Sync talking about the Navy, saying that it is out there every day protecting them from Godzilla, pirates and jellyfish. Lance Bass then reveals that the band has signed JC Chasez up for the Navy and two navy MPs drag Chasez off screeching.