While reading this rulebook, most of the time I spent trying to figure out that this book needed a review by me. Is it even a book? It does have an ISBN, so there's that.
This is the most comprehensive rulebook for the specific beer-pong games named "21 cup". It covers the setup, basics, overtime and a few edge cases. "21 Cup" is enough for one to start playing the game and to get to the champion's belt.
I don't drink alcohol, so the game itself doesn't sound fun — but I hope some of my readers find this rulebook peculiar enough to acquire.