The following description was taken from: http://improveverywhere.ning.com/grou... Improv Everywhere is a national group that has done group freezes, MP3 experiments, and a ton of brilliant group improv events in public settings. Since 2002 they have had an annual No Pants Day where they get a bunch of people to ride public transportation wearing colorful underwear, acting like everyone just happened to forget their pants and there isn't anything particularly odd. For No Pants Day 2009 they are trying to get other cities to participate. Magically, Phoenix will have our light rail working by then, which has to be an omen if I've ever seen one.