Slim began his role in the alien invasion using shadow puppets. He was entertaining a group of people with shadow puppets from a rabbit, an elephant, George Washington and his crew on a boat crossing the Delaware River, a dancing lady, and then a Tyrannosaurus rex. Police Officer Hanson and Mike Tobacco, the film's protagonist, saw Slim use the Tyrannosaurus shadow puppet to swallow up the humans that were watching. The helpless humans appeared as popcorn in Slim's hand which he then puts inside a bag with 100s of other popcorn and their screams were heard. Mike became extremely terrified at this, trying to run over Slim with Officer Hanson's police car, but Slim was able to jump up the entire building where his shadow puppet was laid upon to avoid getting hit.
Later, Slim was seen pretending to use an incredibly fast motorcycle to knock down a helpless driver off a bridge causing his car to explode with Slim laughing maniacally.
Later on, after Debbie was running away from the Klown offspring that had hatched in her bathroom, Slim was using a voice that sounded just like Mike's that said, "Debbie Debbie, it's Mike open up" making Debbie open the door but realizes that it was Slim who was saying it. Debbie slammed the door but Slim tried to knock it down, then Debbie tried to jump out the window only to find Bibbo, Rudy, Shorty and Chubby in firefighter helmets using a trampoline as an alternative back-up. Slim then grabbed Debbie who was screaming while he laughed, throwing her into her couch. Slim had used a device that encased Debbie inside a balloon, which was so that they could turn Debbie into a Killer Klown for sexual purposes just like they have done with several other human women.
Slim had driven away inside the Klown Car and faced a policeman who was refusing to let them access into their Big Top headquarters, who the five Killer Klowns inside considered him as a pest. Slim, Shorty, Fatso, Rudy, and Bibbo took out their corrosive pies, throwing them at the police man who asked, “What are you going to do with those pies, boys?” which killed the police man then Slim carried the balloon carrying Debbie inside and went into the Big Top. Slim was then seen with a bent golf-club like weapon trying to get Mike, Debbie and Officer Hanson, but he was also distracted by the fake plastic head of Jojo on top of the ice cream van driven by the Terenzi Brothers, who had ordered the Killer Klowns to halt their attack. When Klownzilla came in, Slim had left along with all the other Klowns. He died at the end of the film when Klownzilla exploded making the Big Top burst into flames.
- Slim probably killed hundreds of humans using the Tyrannosaurus shadow puppet and the scene where he was shown doing so to passengers waiting for a bus were part of his last victims.