Shorthand for Burning Man, a festival over Labor Day weekend (and the week previous). It started in the 1980's, and the 2007 event had 47,000 people. It occurs on several square miles of dry lake bed in northern Nevada - the Black Rock Desert. The community (4th largest city in Nevada) is called Black Rock City. Burning Man has incredible art, hundreds of pieces, such as one of 2007's: a 100 foot oil derrick 'worshiped' by 30 foot metal sculptures of people, all of which was blown up/burned on Labor Day weekend. Many unusual vehicles drive over the dry lake bed, such as mobile Couches, Dragons built on bus chassis, bakers dozens of moving Cupcakes, Unicorns, etc. Everyone is a participant - no spectators. Nudity is common, appropriate given the heat. There is no vending - it is a gift economy. Burners, as BM folks are known, share a common spirit of freedom, art, self reliance, self expression and a generous spirit.
"I just got my BM tickets!"
"I was at BM from 1999 through 2007."
As seen on a bus heading up to BM, "BM or Bust!"