A bunch of teenagers were roughhousing on a sidewalk along the main drag in my neighborhood. One of them ran backwards, zigzagging, into the street as I was passing. Try as I might to steer from side to side away from him, he kept zigging and zagging until I slammed into him and went down fairly hard. He said, "Sorry, sir," when I back on my feet and rolling away. Last thing I heard him say: "Did he hit me on purpose?"