He was originally Krusty the Clown 's sidekick, before starting a life of crime that began with an attempt to frame Krusty for armed robbery. Bob is a self-proclaimed genius, member of the Republican Party, champion of high culture, former children's entertainer-turned-criminal mastermind and Bart Simpson 's nemesis. He loves operettas, the likes of Gilbert and Sullivan, and is also known for his gigantic feet, which have gotten him into trouble on more than one occasion. His younger brother, Cecil , was actually the one who was auditioning for the role, which Krusty was not impressed by and saw Bob as the ideal comic foil who would be ridiculous and never stand him up. Sideshow Bob soon began to tire of these antics, and also realized that off-camera Krusty was engaging in vulgar behavior such as illegal gambling and patronizing strip joints.