1. Stephen King’s ‘It’ was originally published under a different name. However, an early edition of the book was invited to a book party at which various volumes were playing a game of 'it’ and/or 'tag’. 'It’ was tagged and, as a rather large and ponderous volume, was not able to bounce fast enough to tag any other books in turn. Although 'It’ has attended many book parties since in an attempt to get its original title back, it has not yet been able to do so. But keep an eye out: maybe, someday soon, some other book on your shelves will be called 'It’.
2. Every twenty-seventh copy of 'Harry Potter and the Prisoner of Azkaban’ on sale is actually a small box containing a compressed house elf and a spell to make readers believe that they have finished the book. This scheme, part of a wider effort to disperse house elves more widely among the non-wizarding world, has been in place for some fifteen years. The spell is rather imperfect in its effect, so you can sometimes tell if you have one of these copies by how well you remember the plot of the book.
3. It is nearly impossible to keep the Complete Works of Shakespeare on a shelf together without one of them eventually stabbing another one. Savvy librarians often use stab-proof inserts between copies to prevent book damage. Titus Andronicus is particularly notorious for its scrappy nature, and has been known to spring off the shelves in an attempt to grapple with the works of Kit Marlowe from above.
4. If you leave a copy of the Lord of the Rings in an area thick with marijuana smoke for a few hours and then give it a good shake, you can sometimes get a sleeping hobbit to fall out. If this happens, you should make sure to carefully insert the hobbit back where they fell out from, or the story may be irreparably changed. For example, copies from which Frodo has been ejected sometimes mutate into biographies of a heroic band of orcs, perhaps demonstrating that histories are usually written by the victors.