Reactions to getting cut off

Saturday, late in the morning, yoga mat rolled up and slung over my shoulder, cruising down a neighborhood street. On my right a dark blue slate colored BMW sedan pulls to the edge the street from condominium common driveway. The driver looks me right in the eye, or so I thought. Given my speed, he should have waited until I passed, but he didn't. He took full advantage of his engine's power and cut right in front of me. A little ABS braking and no harm done. My left hand lifts off the handlebar and I wonder it is going to do. Holding my hand in front of me so that he can see it in his rear view mirror, I wag my forefinger back and forth a few times, "not good, fella, not a good move".

We are approaching the intersection. If he's a local guy he knows that this traffic light is not generous, it is likely that he and I will be side by side for a while. He doesn't know I'm going to turn right. His left turn signal starts flashing and he moves over not one but two lanes. He's in the left turn lane now, safe from my withering gaze thanks to a minivan that has arrived innocently to this heated swirl of intentions and annoyance.

A few years back when I was commuting regularly on the highway, a cop pulled up next to me and wagged his finger at me. My visor fogged from the humiliation I felt in response to that gesture. I was speeding, not much, but I was at the edge of highway cop tolerance. Adults wag their finger at children to convey shame, "you are old enough to know that you shouldn't be doing that". Finger-wagging strikes me as richer that just leaning on the horn.

I will never know if Mr. BMW sedan driver actually intended to turn left or not. When he checked over his left shoulder for oncoming traffic he does not appear to have seen my motorcycle. Or maybe he misjudged my approaching speed. Unfortunately, that's typical. Getting cut off is something that riders have to anticipate. There's a surge of emotion, first surprise, "are you crazy?", followed by a conscious effort to focus and avoid a collision ("thank heaven for ABS"), followed by a flash of anger ("you idiot") that dissipates to annoyance, followed by an indulgence in finger-wagging, followed by wondering if I have cut off anyone recently, and finally a miffed acknowledgment that it is time to take a safety class and practice swerving.

[Feb 3rd update: This response came in from Jim Thurber: "... After riding bicycles for these last few years when somebody cuts me off I do one of several things:
a) If I can catch their eye I wave, a big friendly wave along with a huge smile.
b) If they cut me off so closely that they're right NEXT to me, I tap (gently) on the side of the van. Women seem to ignore it. Men frequently SLAM on their brakes, sometime actually stopping. "Gee Sir, I'm sorry," I'll say. "But you ran into me. I was able to jump out of the way though, so your car is OK."
c) If they cut me off and park, I'll pull up and approach them, holding out a dollar and "thanking them" for not killing me. I usually assume a foreign accent and explain that "In my country it is considered important to tip somebody for not killing you . . . . ." I've had people go absolutely berserk when I do this . . . but hey, it's fun."]