Captain Underpants and the Attack of the Talking Toilets (Captain Underpants #2 Color Edition) by Dav Pilkey

George and Harold are usually responsible kids ... whenever anything bad happens George and Harold are usually responsible! And it looks like they're up to their old tricks again! First, they ruined the school's science fair with a series of silly pranks. Then they accidentally created an army of evil, vicious talking toilets, intent on taking over the world. Who will stop the carnivorous commodes? This looks like a job for Captain Underpants!