Big Nate Flips Out is an upcoming Big Nate book. This book will be coming after Big Nate Goes for Broke, and it will be Book #5. Not much is known, but the book was first announced on the Big Nate website, and on the "About the Author" section. It said this:
Point #2: Now It’s Time To Start Writing Book 5! As I think I’ve told you before, Book 5 is going to be called Big Nate Flips Out. I’ve written a two-page sneak peek about the story (you can read it at the very end of Goes For Broke), so I have a vague idea of what the book will be about. It’s going to deal in some way with Nate’s sloppiness. And Francis will play a big part in the book. That’s about all I’ve decided so far!