I recently wrote a review of Douglas Adams' The Salmon of Doubt on Amazon.com, and in said review I mention a neat trick that you can do with the original paperback cover to The Hitchhiker's Guide to the Galaxy. The trick takes innocent cover art and turns it into a bum. Well, there was enough interest in this little parlor trick that I felt I should post about it in more depth here.
Step 1: Buy the Paperback.
Step 2. Turn it Upside down.
Step 3. Stick it in a seat-pocket.
I discovered this when I was nine, on my way to a family vacation in Disney Land, this made me laugh so hard I sprayed my complimentary beverage out of my nose.