I had something similar also happen to me. I was on the way home from an estimate and accidentally got a little close to a guy in a pickup truck. You know when the traffic slows a bit and you don't jam on the brake but kind of drift a little close to the person in front of you. I then let off the gas and coasted back to a reasonable distance. Then splat......the guy spits a huge mouthful on my car and windshield. That was a mistake as I keep my car in pristine condition so I flew past him and brake checked him. Not just a run of the mill brake check but a few hard ones and then I stopped in a 6 lane road and sat for a few seconds. Everybody on the sides and behind also stopped and I imagine were wondering what was going on. I then proceeded to take off out of there with full throttle leaving him as a tiny dot in my mirror. He eventually caught up and then stayed close behind me a few cars back. Without thinking I turned onto my street and realized the nut was following me right to my house. I went past my house and parked in a neighbors diveway so he didn't know where I lived. Shouldn't have done that but when he turned down my street it caught me off guard as I believed we were even. Spit on car for hard brake check. He stops and yells out the window "Now I know where you live, I'll be back tonight to get you" or something to that effect. Then he quickly waved something that I thought was a gun in his truck at me. I was sitting in my car with my Sog tactical knife waiting for the nut to come at me in the car. I popped out and said "come on back", waving the knife and smiled. He then took off and I realized I can't let this guy really come back so I started calling 911 as he took off. I chased after him getting his plate number and wouldn't you guess it as we turn the corner from my street there is a state trooper at the scene of an accident. I don't know how I missed it on the way in. So the guy quickly stops there and jumps out yelling " He has a knife!" I jumped out too and said "he's got a gun." After searching the vehicle they didn't find a gun but he sure had something that he held like a gun and sure had a silhouette like one. Of course I didn't hide the knife and it was confiscated. In the end after she got both sides of the story she said neither one of us better make contact in any way or else theres going to be trouble. It turns out throwing anything or in this case spitting something at a vehicle that can be washed off is not illegal. The trooper said although not nice even an egg that can be washed off is OK. Funny, though if you spit on a cops car guess where you'll be spending the night with probably 10 tickets for anything/everything possible in the book.