I was commuting in on my bike, and was easing up to a red light at a busy intersection in downtown DC. A commuter on a mountain bike blows past me up to the intersection. Instead of stopping at the intersection, he starts cycling in circles in the crosswalk until he sees a break in traffic, then goes half way across the road. Now he is in the middle of the intersction, stopped, with traffic flying by him in both directions. Finally there is a small break in the traffic, and he swerves between some moving cars to continue up New York Avenue. By then, the light has changed so I cross the intersction about 15 seconds after him and follow up NY Avenue. I get to the next intersection (red light) and there he is again, doing the same thing: circling in the crosswalk, then crossing traffic half way, then stopping in the middle of the intersection, then bolting through moving traffic to go through the red light. Why in the world would he ride like that to save, what, 15 seconds?