Mr Gum and the 13-Storey Underpants

Mr Gum and the 13-Storey Underpants is a 2021 book published by Scholastic. It is a crossover between the franchises Mr Gum, Storey Treehouse and Captain Underpants. Later on it crosses over into Jedi Academy

Trivia

 * despite the fact that the Turbo Toilet 2000 has consistently been shown as working with Tippy Tinkletrousers, he does not in this book (rather working with Professor Stupido) because in the original books, they never met.
 * It is a what if scenario where Stupido is sent to Uranus instead of The Moon in 39-Storey.