The May Day Mystery.

The May Day Mystery refers to a series of cryptic ads which have been placed in the Arizona Daily Wildcat, the newspaper of the University of Arizona, every May 1 since 1981. (In 1983, 1988, 1999 and 2005 the ads technically ran on April 29, April 27, April 29 and April 29, respectively. May 1 first fell on a weekend in those years, when the Daily Wildcat does not publish.) The ads have appeared on other dates as well, usually in early December. While the ads at first appear to be an intellectual game, there is an underlying message of political and economic revolution.

This ad ran on April 27, 1988 (high resolution ad here)

The first ad contained three handwritten lines: "SR/CL: RICHMOND", a string of Simplified Chinese characters, and "MAY DAY, 1981". The Chinese characters translate literally as "Chairman Mao ten-thousand years old", which is usually interpreted as "Long live Chairman Mao".

There are a number of recurring themes in the ads, including:

* The Orphanage: A secret society, supposedly behind the ads

* The Prize: An unspecified reward for anyone who "solves" the mystery; in a safe deposit box

* Smiley Guy: A stylized smiley face that appears in some of the ads

* SR/CL: An unknown acronym

* White Rabbit/Wonder Bread: Unknown commodities transported by the Orphanage

* Martin Luther

Bryan Hance, a former student, discovered the ads as an undergraduate and is the first person known to seriously investigate them. He started a website in 1997 to document his investigation, and has attracted a small group of followers. He has been in contact with "The Orphanage" and others (such as "the Pimp") by email, post and phone since 1999. He has received many packages in the mail containing everything from photographs, coins, photographs, and printouts from websites. He has also received many gold coins and bills, totaling over a few hundred dollars. He has been told that the money can be spent any way he wants, however, Bryan tends to use it on paying the server bill.

The ads are placed by Robert Truman Hungerford, an eccentric lawyer who claims to be the legal counsel for the organization. While he refuses to discuss the origin of the ads, he has said that it is possible that he is insane and that the ads are "the ravings of a madman".

Source - Wikipedia.

Why People Believe Weird Things: Pseudoscience, Superstition, and Other Confusions of Our Time