In the 1950, radio host Jean Shepherd played a great prank on New York City bookstores. Annoyed with how bestseller lists worked at the time, Shepherd urged his listeners, aka "the Night People," to descend on all bookstores requesting a book that didn't exist. He even gave them a plot summary, author, and title. Eventually, the fake book "I, Libertine," became a real bestseller. WFMU posted a 1968 radio show of Shepherd telling the whole fantastic story.
I, Libertine hoax (Thanks, COOP!)