When Captain Underpants was instructed to get this invention to make the school grow back to normal, the Professor zapped him and the Goosy-Grow with the Shrinky-Pig 2000 making both smaller. The now small invention landed in George's hand, but he figured out how it works and what he and Harold must do. They are thrown off the roof of the school by the Professor when they to try to get the school back to its proper height. Harold quickly made a paper airplane which George enlarged with the Goosy-Grow 4000. Later they tried to make the Captain bigger so he can fight the Professor. Captain Underpants landed on Harold's finger, but when George aimed the Goosy-Grow at the Captain, he accidentally zapped Harold's right hand, making it bigger. George then zapped Captain Underpants a few times ti