The theory: In 1997, Bryan Hance, a student at the University of Arizona, began to investigate cryptic ads that run every year on 1 May in the student newspaper, The Daily Wildcat. After a bit of research, he found out the ads go back as far as 1981, potentially further. It's still going on today, and you can see the 2016 May Day ad here. The theory is that the ads are communication between a group of intellectuals, and Hance believes the ads contain meeting dates, past and future, for a secret society that is planning for an economic and political revolution. Hance tracked the ads for the last 10 years to a lawyer, Robert Hungerford, who claims to have no involvement with the creation of the ads, but says he is just asked to send them to publish.
Any proof? Most ads feature incredibly obscure historical references, symbology, and mathematical calculations, so it's likely they aren’t just nonsensical ramblings but are the result of a deliberate, careful effort. Hance and a friend working with him were contacted in 1999 by a member of a group called The Orphanage, saying that the adverts are part of a larger cause, and the group have supposedly sent him clues and donations over the years. A letter to Hance from The Orphanage ends with the sentence, "The day you can see the door, you will be welcomed inside."