Good idea, jo. I have yelled at cars before. In one instance, I was going straight and a car was getting ready to make a right into my path and wasn't looking my way (I was just going past his line), so I yelled at the top of my lungs and he heard me and stopped. His window was open, so I was pretty sure he would hear me. Not always the case. I didn't have time to stop, though, so it seemed like the best thing to do. My 3 year old has a pink squeaky pig on her trike handlebars... maybe I need one of those! I do know of a couple of people who have some sort of air horn for such occasions.