Bring Your Own Big Wheel.

Apparently, a couple of days ago on April 8, 2007, there was the 7th Annual Bring Your Own Big Wheel event, where over 100 people converged onto San Francisco’s Lombard Street [wiki] (The Crookedest Street in the World) to race!

Links: JonBrumit (warning: annoying music on webpage) | jwz | Laughing Squid