A guy here at work that retired last year at the age of 54 was a big fan of Burning Man. My understanding through him was that for one week a year they head out on a dry lake bed in Nevada and set up camp. Everything you need for the week has to be brought in including food, water, entertainment, building material etc. Camps are built around the Burning Man effigy at the center of it all. Groups have clubs that you go and party, and drink at round the clock. Some groups have breakfast, lunch or dinner, and its all free. At the end of the gathering they set torch to the Burning Man and the next day everything is cleaned up with no traces left behind and its over till next year. Goggle and masks are needed to be kept with you at all times because you never know when a sand storm will kick up.
Supposedly it originates from a guy in San Fransico who after breaking up with his wife or girlfriend went to the beach there and built the first burning man. He sat there comtemplating life and set it on fire. Others heard about it and it grew to a point where they had to move away from San Fransico and eventually wound up in the desert. It has evolved into a really big cultural event and perhaps has lost some of the original meaning but according to my friend is a great party.