I hit the rear end of a very pretty Cadillac, while I was trying a California thing called "lane splitting." I didn't do it very well, should have allowed more room between me and the car in front before I ducked between lanes. I saw another biker doing it, then said, "heck, I can do that." Then I glanced back to see if there was another bike following the first guy. That's when the Cadillac hit his brakes. Whoops. Interestingly, the bike didn't go down. Somehow I hopped off the bike and held it up. I don't remember how.