Hallowed Books are very special books, often coveted by religious people. They use them as a place to hide their stuff.
Hallowing a book is actually a lot of trouble. The process involves sharp objects and gluey adhesives, and can be mind numbingly tedious. Leave this difficult task to those who are spiritually strong.
If you are persistent enough to hallow a book, or are lucky enough to, er, *find* one lying around, it is wise to put it to proper use. First off, you should inspect your book, and see if there is anything blessed in the hallow. To do this, lift the lid (carefully!) and look inside. If there *is* something in your hallowed book, Hurray! Unless it's C4. If there isn't something in your hallowed book, you can put something in it. Often people put Marijuana in hallowed books. It's sort of a sacred secret spot. Get it?
In addition, some of the most classic crimes have been committed via hallowed-out books. For example, when John Wilkes Booth was murdered by President Lincoln, Lincoln gave Booth a book called "The Emancipation Proclamation". While this sounds like it would be about someone shouting "I'm HUNGRY!!!", it was actually about the plight of the African-American slaves in Amerika. Unfortunately, Booth shouted "Hurray!" before spying the C4 inside of it. He made a mural on the wall.
Oscar Wilde was master of the Hallowed Book, and created more than fifty-seven of the tomes. Perhaps his most famous was a novel entitled Totty, both written and hallowed by him. He sold it to a man cleverly calling himself Yttot, never suspecting that it was the mastermind of crime and subject of the book himself, Totty. Totty used the hallowed Totty book to hide the bullet he later spat at JFK, killing him dead in Dealy Llama plaza.
It is also worth noting that the hero in "The Shawshank Redemption" uses a hallowed-out-book to stick it to the man. This is also known as Sporking.