Captain Underpants and the Preposterous Plight of the Purple Potty People by Dav Pilkey
The Purple Potty sent Harold and George to an upside world! Teachers are kind and nice and also Mr. Krupp! They also saw their evil identicals!
I’ve borrowed this from my cute cousin, Brill. I lent him my other Captain Underpants books and he became addicted to it too! He bought this book with his own money (take note: he’s 8 — not sure!).