In this worthy sequel to The Adventures of Captain Underpants, Pilkey maintains the original's satiric, self-referential formula as he revisits fourth-grade pranksters Harold and George, along with their school principal and principle nemesis, Mr. Krupp (aka superhero Captain Underpants). Trouble begins when Harold and George sabotage a science fair and are punished with "The Invention Convention Detention." Bored, the boys collaborate on a comic book about Talking Toilets. To their surprise, the Toilets come to life and Mr. Krupp's alter ego is called into service. Worst of all, even the brave Captain Underpants may be no match for the Toilets' leader, "nearly a ton of twisting steel and raging porcelain" known as the TT 2000. Pilkey illustrates in uncomplicated black-and-white line drawings with washes of gray, and offers "Flip-O-RamaTM," which requires turning a page back and forth for low-low-budget animation ("Don't forget to add your own sound-effects!"). He promises "extremely graphic violence" in scenes of "a giant toilet getting its shiny hiney kicked," ridicules teachers named "Ms. Ribble" and "Miss Anthrope" and decides that the story just wouldn't be complete without "upchucking." Bart Simpson could learn a few things from the subversively hilarious Harold and George, who consider inventing a robot urinal ("The Urinator"), then decide, "They'll never let us get away with that in a children's book. We're skating on thin ice as it is!" Ages 7-10.