I did that once by my old place in Adams Morgan-- some guy threw a soda bottle out his open window at a red light. I walked over and handed it back to him through the window, "I think you dropped this." He threw it back at me. I handed it back to him. He got out of his car. I used my usual, "what are you going to do, hit a girl? dude, I *live* here. go litter in your own neighborhood." woah, was i glad the light changed at that point.