He makes the gerbil machine as large as a tall building, then shrinks the school and holds them hostage to turn their names sillier, with a system of three alphabetical name charts based on the first/last letter of each part of a first and last name. George and Harold (now Fluffy and Cheeseball) get Captain Underpants (now Buttercup Chickenfanny, but refuses to take the professor's order to change names) to steal Professor Poopypants' enlarging machine, but he and the machine are shrunk in the process. The two of them try to enlarge the school back to normal size, but get flicked off the school. Cheeseball makes a paper airplane that Fluffy enlarges and after many dangers, Underpants rescues them. Fluffy enlarges Underpants to the gerbil's size, then he defeats Professor Poopypants and everyone's names revert. The boys use the machines to bring themselves, the school and Captain Underpants back to normal size. Captain Underpants is soaked with water, turning him back into Mr. Krupp.