I was waiting for the bus to take me home today when I noticed two WMATA employees chatting to passengers at the stop while simultaneously monitoring radio traffic on their sets. Apparently, a series of manhole covers had exploded on 16th st, derailing traffic.
As they stood and joked with the riders, a car driving down 14th st hit his horn in frustration that some pedestrians weren't walking fast enough. Immediately, one of the WMATA guys looked over and said to the car, "Hey, where do you think you are? New York? This ain't New York! That's not how we do it!" to which the other riders all chimed in with their stories of how New York drivers stank, or of "that time" they saw someone in DC incongruously hitting their horn in a non-DC fashion.
Second only to our habit of waiting in lines patiently, people here simply do not use their horns. It's what makes DC such a great city. (The downside is that this similar level of politeness extends to the metro escalator system...DC riders never do more than simply cough when someone stands on the left-hand side)