I have read this book and it's so good mostly it's about Harold and George's gym teacher Mr. Meaner eats something that makes him smart so he makes this spray that makes your kids more focused on work and things important but the effect does not last very long. So he makes this machine that he uses to spray kids but he does not use until Harold and George make him so mad that he uses it to spray everyone. They try to get adults and their first Idea is to get their parents but they see their yesterday selves were already showing their parents how good they are. Then their parents liked the yesterday versions so they went in the future where they see their adult selves. They learn that George in the future is an author and Harold in the future is an illustrator they read one of the novels before they go and they comment that it's good for old people. Then the old versions of them begin to question them as they go save the world when they get there the get captain underpants and they fight Mr. meaner