Security guards the bumbling and overweight Chuck (Gailard Sartain) and the taciturn Bobby (Bill Byrge) play a game of Red light/Green light while being night watchmen for Howard County Bank and Trust and are obsessed with elaborate schemes of would-be thieves. They hear a sound coming from a floor polisher that Ernest P. Worrell (Jim Varney) (who works as a night custodian but dreams of being a clerk) is trying to turn on for operation, but he ends up making a mess in the bank and he becomes magnetic from a mishap with the floor polisher.The next day, bank president Oscar Pendlesmythe's assistant, Charlotte Sparrow (Barbara Bush Tyson) orders him to clean up his supernatural mess. Pendlesmythe (Dan Leegant) arrives and wants to terminate Ernest's employment at the bank, but Charlotte has a soft heart for misfits and stray dogs, so she argues on his behalf.Ernest takes a bath at home in a tumble dry washing machine and uses a blow dryer with a wind tunnel force for his evening dinner with Charlotte in a restaurant. He later receives in the mail a summons to jury duty in court and tells the two watchmen about it.During the trial, Dracup Maximum Security Prison convict Rubin Bartlett (Barry Scott) notices that Ernest is a dead ringer for death row inmate Felix Nash (Jim Varney in a dual role) and has his lawyer convince the jury to tour the prison, where Ernest is kidnapped by Nash and another inmate named Lyle (Randall 'Tex' Cobb) and forced to switch places with Nash. Even though he tries to tell the guards he is not Nash, they refuse to believe him. Ernest also does not know that he has a death sentence, which is for Nash.While having lunch, a guard tells them to stand up and be quiet, when he notices Ernest is making a lot of noise, which almost sends him into the cell. Ernest tries to tell one of the prison guards that he is Ernest, not Nash, but the guard calls him "Mr. Funny Man" (which is a mistaken lie), angrily says that he is not funny, and is lying and throws him into the cell right in front of Lyle, who pushes him back. When he pushes him near the prison bars, he tells the guard that he was beaten up (and accidentally slamming the guard's head on the bars). The guard tells Ernest that he will be sent to the hole, which makes Ernest realize he is in jail. Bartlett tells him that Nash has assumed his identity and warns him to keep his mouth shut.Ernest makes several unsuccessful escape attempts, and is soon sent to the electric chair by the prison warden (Charles Napier). The electrocution fails, and Ernest is transformed into a type of superhuman, with the ability to shoot lightning bolts from his hands (that Ernest named himself 'Electroman'). To make his getaway, he blasts a hole in the main gates. However, Bartlett obstructs the escape and attempts to kill Ernest himself, only for Lyle to intervene, knock Bartlett unconscious and allow Ernest to make his escape, knowing that Ernest is different from everyone else. Lyle decides to stay behind because (speaking for the first time) he tells Ernest that he have been in prison most of his adult life and "doen't belong out there". Ernest says goodbye to Lyle and escapes just before Lyle is detained by the prison guards.Making his way home, Ernest discovers that his Pee-wee Herman-like decor has been replaced by a slick Lounge Lizard style of decorating and exclaims, "I've been vandalized - by Elvis!" Meanwhile, Nash is preparing to blast open the bank's vault with a time bomb, with Charlotte and an unconscious Chuck bound nearby. Charlotte begs Nash not to go through with it, and he blurts the truth about being an impostor. Charlotte doesn't believe it until he points out he's done a far better job cleaning the floors than Ernest ever had. Ernest arrives and he and Nash do battle. Ernest gets electrocuted yet again when Nash harshly throws him against an electric cage that the bank had rigged to drop from the ceiling to catch robbers. Now Ernest has become polarized and gained the ability to fly. He uses his super powers to fly through the skylight of the bank with the bomb which leads to a spectacular mid-air explosion. Everyone especially Chuck thinks that Ernest has been killed, until he falls through the skylight and lands on Nash, which leads the warden and the guards to find out Ernest was right all along. Ernest tiredly declares, "I came, I saw, I got blowed up." and then faints.