One day Deuce goes psycho and when the dust clears, Zack's undies are on the outside of his clothes instead of the inside. Soon their creation “overpants” is a massive hit and everyone wants to wear it. Zack even becomes the face of their new fashion creation. But when a heat wave strikes and shrinks all of the underwear, suddenly everyone in town has an atomic wedgie! And worse still, their butts are trapped in a cotton blend prison. Now the guys have to get everyone to ditch their haute couture to save the butts and the town. / Zack and Deuce are messing around in Silas‟ secret lab when Zack accidentally tries on a prototype robo-butt. And it's awesome! (Although Deuce is kinda jealous.) Zack is loving his cool new synthetic butt, so much so that he goes all out with the upgrades and soon his butt gains sentience, becoming all Mom-like to the point that she's running the show! She bans Zack from butt fighting and holds him hostage! Now it‟s up to Eleanor and Deuce, the old butt, to save Zack from his new shiny, metal cheeks.