Rudy and Slimer stop at a hot dog cart, where the vendor charges Slimer $1.50 instead of the standard $0.75 on the grounds that he is a ghost. The vendor gives them an hour to pay or he will call the police. Worried about ending up in jail, Slimer grows anxious until Rudy notices a street performer with an organ grinder and a pet monkey pickpocketing the crowd. Rudy gets an idea: he builds his own organ grinder and persuades Slimer to act as his monkey in exchange for ice cream. The duo draws a crowd and earns enough money.
The competing organ grinder is not pleased. He sends his monkey to sabotage Rudy's machine by flipping an internal "Uncool" switch, which drives the audience away with unpleasant music. Rudy hits an emergency kill switch, identifies the problem, flips the "Cool" switch, and Slimer wins the crowd back with his dancing.
The organ grinder then complains to a police officer that Rudy is operating with an illegal monkey. The officer pulls out his police manual. After consulting it, he concludes that Slimer is a ghost, not a monkey. He then notices the organ grinder and his monkey stealing from bystanders. The organ grinder insists his animal is a dog, but the monkey itself points out the monkey entry in the manual, sealing their fate. The officer arrests them both. Rudy and Slimer continue to entertain the crowd.
Rudy (voiced by Jeff Marder) is Slimer's human companion and the inventor of the impromptu organ grinder scheme. He handles the business side of the act and figures out how to defeat the sabotage from the competing organ grinder.
The Organ Grinder (voiced by Charlie Adler) and his pet Monkey (voiced by Frank Welker) are the episode's main antagonists, a pair of street entertainers who supplement their income through pickpocketing. Threatened by Rudy and Slimer's competing act, the Organ Grinder sends his Monkey to flip the "Uncool" switch on Rudy's machine and later files a false complaint with a police officer claiming Slimer is an illegal monkey. The scheme backfires when the officer's police manual confirms Slimer is a ghost and the officer catches the pair mid-theft. Both are arrested.
The episode features Rudy's custom-built organ grinder as a central prop. The police officer's police manual plays a key plot role, notably containing a photograph of Slimer in the ghost entry.