In Australia, it's not uncommon for cars to drive as close as they can to you, beep their horn at you, cut you off or shout obscenities at you as they go by. Some cyclists may retaliate by shouting back, flipping the bird, riding even slower or giving a sarcastic friendly wave. This generally results in a mutual hatred for each other before driver and cyclist continue on their separate ways.
Here in America, things are a little different. Cars still hate cyclists and drivers still shout out obscenities. But there is a big reason why, as a cyclist, you should not retaliate.
The driver could be carrying a gun. America's gun laws mean that any driver could have a gun with them and you do not want to aggravate that person.
You don't want to take this risk and annoy the wrong person because you could get a surprise.
During a ride, I have already seen one driver get as close to us as possible while pretending to shoot us by using his fingers as a pistol.
So we just look straight ahead and keep pedalling. (Of course, retaliating to bad drivers is not something that we do anyway as that is just wrong)