I was riding my bike on Santa Monica Blvd tonight and had a car actually do me a favor...instead of practically run me off the road.
In West LA, SM Blvd has those little side roads that join the main road. There's a yield sign at each of them, but most people just come right out and try to get on the main thoroughfare.
I was riding dead even with a Mercedes SUV on the main road and this car came flying down one of those side roads ready to merge. Mr. Mercedes honked (aggressively I might add) at this guy and pointed at me and then shook his head at the speeding guy.
Thanks for looking out! Most definitely an uncommon gesture.