The Oz book test is a unique version of a booktest.  I perform it as a stage piece, I 'toss out' the book and ask an audience member to check to make sure it is real.  Unlike many booktests this book is entirely inspectable, and reads from cover to cover as 'The Wizard of Oz'.
 
You don't need to see the book.
You don't need to be anywhere near the person holding the book.
You don't even need to be in the same room as the person with the book!
 
Oz is a booktest unlike others, which can be repeated over and over with different reveals all of which are entirely relevant to the story.  
 
Oz is both a workers dream and a magician fooler too!