In its simplest form, it's a 12k race from one end of San Francisco (the Bay) to the other (the breakers at Ocean Beach) in mid-May. In reality, it's a race for only a few hundred people, with the remaining thousands out for a running, rolling street party from one end of San Francisco to another. Many of the participants run in costume, sporting everything from sequined dresses to nothing but shoes. Others join one of the many groups participating in the costume contests. Most frequently, the group costumes include a keg as well as a wet bar.

Along the course, residents set up their own wacky contributions, ranging from impromptu game shows to a lip-synched dance routine to the Village People's "YMCA." The last portion of the race winds through Golden Gate Park, where local bands entertain the throng. You needn't be a runner to participate in the fun--at least half the crowd simply walks the course.