You should only use the horn as a warning in case there may be an accident. Blowing the horn just because you are mad may startle someone into having an accident. It could also anger some nutjob who decides to start shooting at ya.

Technically, the horn should only be used in order to prevent an accident--that is, to warn another driver of danger in one form or another. And, while it may be tempting to lay on the horn after another driver cuts you off, you won't do yourself any good. Not only do you risk retaliation from the other driver, but you can also cause yourself significant stress. Over time, stress can be really detrimental to your health.

According to WebMD's Louise Chang, MD, "Stress that continues without relief can lead to a condition called distress -- a negative stress reaction. Distress can lead to physical symptoms including headaches, upset stomach, elevated blood pressure, chest pain, and problems sleeping. Research suggests that stress also can bring on or worsen certain symptoms or diseases."

I suggest that instead of allowing yourself to be stressed, you intentionally relax when something like this happens. It's not worth the trouble--and if it helps, think about this: you don't really know what's going on in the other driver's head or life at that moment. He could have just lost his job or even a loved one--or maybe he's on the way to the hospital to watch his child come into the world. Other drivers are people too, and most aren't horrible. They're just like everyone else. Sometimes, quiet compassion is the answer--and remember that what you send out into the world comes back to you. :)

Actually I normally would have honked and even given a "finger" but I have been told that you have No idea what state the other driver was or is in at the time and it could be quite dangerous as the other driver may decide to pursue you and attempt road rage of any degree.

I would suggest "grin and bear it"

I would honk. The other driver might not be very alert and maybe needs someone to wake them up so to speak. I can not stand people that cut others off or that do not yield at the proper times. I also get upset when someone rides on my butt or goes extremely slow. I have often that of making up small but effective driving signs to carry around. LOL. Like the speed is 55, put your phone down and pay attention to the road whatever the situation might be.

Maybe the blowing of a horn could have prevented this.

http://www.flickr.com/photos/wadegriffith/1020050375/