Parker and Stone decided Kyle would be the good student and "school-smarter than the other kids". The subplot with Stan getting beat up by his sister Shelley came from Parker's real-life experiences getting beat up as a child by his sister, also named Shelley, who is three years his elder. Parker said although his sister would later deny it, she regularly beat him up or locked him out of the house for hours; Parker stated that the scene when Stan says "You're my sister and I love you" in order to try to avoid a beating, but was subsequently beat even harder, was based on an actual experience with his sister. The scene in which Stan asks the giant mutant Stan to attack Shelley is based on Parker's childhood fantasy of having a larger version of himself beat up his sister. The resolution to the subplot, in which Shelley takes the blame for Stan's mistakes, and then beats up Stan when he tries to thank her, was also based on experiences Parker had when his sister would bail him out of trouble. The dialogue spoken by the giant mutant Stan was inspired by a mentally handicapped character in the MTV show How's Your News?, which Parker and Stone produced; according to Parker and Stone, the character could only say phrases like "Bubba chop, bubba chewy chomp", and both men took turns voicing mutant Stan to sound the same way. Isaac Hayes, who does the voice of Chef, recorded all his lines via phone from New York; Parker and Stone said they were nervous to ask him to repeat the line, "Now I know how all those white women felt", but he had no problem repeating it. The genetic mutations Dr. Mephesto creates, including the animals with multiple asses and the goldfish with bunny ears, were inspired by things Parker drew during high school. The scene in the cafeteria, in which the four boys are annoyed by Pip, is a cut scene from the original version of the South Park pilot, "Cartman Gets an Anal Probe"; as such, the animation in that individual scene is actually traditional paper cutout stop motion, while the animation throughout the rest of the episode is done with computers. In order to illustrate the aftermath after the destruction scenes, Parker and Stone smudged the paper sets with their fingerprints and stains to make them look like