Plot
At the southwest of Greenland, a scientist from the fictional country of New Swissland (with a foreign culture where everyone has a silly name) named Professor Pippy P. Poopypants goes to the United States to demonstrate how his Shrinky-Pig 2000 and Goosy-Grow 4000 can help the world by reducing garbage and increasing food. Still, everyone laughs at Poopypants' silly name rather than taking him seriously, which is a constant annoyance to him.
Meanwhile, Jerome Horwitz Elementary School is going to a pizza place called Piqua Pizza Palace, George and Harold decide to rearrange the letters on the nearby sign during the wait to get on the bus, but Mr. Krupp catches the boys and bans them from the school field trip, tasked with cleaning the teacher's lounge for the rest of the trip. However, the boys set up a prank as payback for the teachers by "modifying" things in the teachers' lounge. After the trip, the teachers fall into George and Harold's trap and get largely covered in powder paste and Styrofoam pellets. The teachers run out of the lounge in horror chasing George and Harold, causing Mr. Fyde, the science teacher who was on bus duty, to witness the covered teachers and believe they're abominable snowmen. He resigns the next day, believing he's losing his sanity due to the incident and having a dream of being eaten by a talking toilet, hearing cats and dogs in the classroom, then imagined that the school flooded with green goop, and seeing Captain Underpants, eventually leading to Mr. Fyde resigning from job and headed for the Piqua Valley Home For The Reality-Challenged prompting Mr. Krupp to find a new science teacher.
Meanwhile, Professor Poopypants finds an ad to teach at the school and applies for the job, thinking children to be kind and sweet-hearted, but they spend days laughing at his silly name instead of learning anything. The professor only gets them interested by building a robot that makes gerbil jog along with them, but the interest is short-lived when George gets him to reveal his middle name (pee-pee). Sometime later, Ms. Ribble reads The Pied Piper of Hamelin, which inspires George and Harold to make a comic about the Professor trying to take over the world using an army of gerbils in suits, which makes Professor Poopypants furious and destroys the last of his sanity.
He decides to use the Goosy-Grow 4000 on the gerbil suit, climbs inside, then shrinks the school and holds them hostage. He then grows a pencil large and writes a system of three alphabetical name charts based on the first/last letter of each part of a first and last name to force people to change their names to silly ones (possibly so that *they* will be laughed at for a change). For example, Benny Krupp is now Lumpy Pottybiscuits. George and Harold, now Fluffy Toiletnose and Cheeseball Wafflefanny respectively, get Captain Underpants (now Buttercup Chickenfanny, but refuses to take the professor's order to change names) to steal Professor Poopypants' Goosy-Grow 4000, but he and the machine are shrunk in the process. The two try to enlarge the school back to normal size but get flicked off the school by Professor Poopypants. Cheeseball makes a paper airplane that Fluffy enlarges, allowing them to fly away, though they face many dangers, barely escaping a woodchipper, a dog, and a steamroller, until Captain Underpants rescues them. Fluffy then enlarges Captain Underpants (and Cheeseball's hand) to the robot's size, then they fight until Captain Underpants defeats Professor Poopypants, and everyone's names are changed back to normal. The boys use the Shrinky-Pig 2000 and Goosy-Grow 4000 to bring themselves, the school, everyone inside, and Captain Underpants back to their normal sizes. Captain Underpants then dresses and is soaked with water, turning him back into Mr. Krupp.
Professor Poopypants is then arrested and hauled off to jail for his crimes. From the advice of George and Harold, he legally changes his own name so that no one will make fun of it anymore. Unfortunately, he changes it to that of his maternal grandfather, Tippy Tinkletrousers, which only makes the prisoners (and police officers) laugh at him even more, much to his anger. Later in the treehouse, George and Harold reflect on the moral of not making fun of people, believing this to be their first story to have a moral.
Comics
The Pied Pooper of Piqua
Professor Poopypants, tired of being laughed at for his name, decided to create an army of gerbils in Gerbil Jogger 2000s. To make them evil, he made them listen to music. The gerbils then attack the whole school and round up all the kids as slaves, so the principal calls for Captain Underpants, after the hero laughs at Poopypants' name, the villain uses his bowtie to transform into a giant cyborg. The two fight and end up in a junkyard, Poopypants tries to crush the hero with the Big Crusher Thingy 2000, but Captain Underpants uses his Tiny Toilet of Truth to spray water on his cyborg suit so it would rust. The music turned out to be Cher songs like "I Got You Babe," he destroys the controller, freeing the gerbils and children, before taking Poopypants to jail.
Reception
The book was removed from an elementary school in Page, North Dakota due to parental complaints.[1]
