Road Rage

I was driving my three year old home from a field trip yesterday. A perfectly normal thing for a father to do. I was coming to a complete stop, checking the cross traffic and doing all of things a parent does that they never did pre-children. Most people take a few liberties with the traffic laws. That is until a child comes along. It's then you realize how import it is to be safe. You have their fragile, energetic little lives at ten and two. So the light turns green and these guys, these punks get up in my back seat and speed around my left. They went into oncoming traffic just to get around Captain Safety. They proceeded to burn through the next two stop signs until coming to a stop at the red. A few moments later I pulled along side of them. I shouldn't have looked. I told myself not to pay them any attention. But I did. I always do. And I had barely forced a sneer and they set to mocking me and yelling at me - like, "what are you going to do about it old man!" So I threw a rolled up napkin at the car. That's all I had. My daughter has a cold and I just wiped her nose. So I chucked it. Maybe I should have looked around for a penny or a pen or a rock - but I didn't think, I just reacted - and threw the tissue. It still could have done a lot of damage. The germs if introduced into a pristine environment could cause a stuffy nose and/or coughing. And I didn't just chuck it - I chucked it with bad intentions. Well they started yelling all the more and now satisfied that I had stimulated an appropriate reaction, I turned right and continued home. WHAT IS MY PROBLEM?! Why did such a careless and foreseeable act get me so agitated? What do I care how they drive? Why did it make me so angry? Anyone?