Last night I was riding home on a 4 lane (two each way) road in my neighborhood. During the day you can park on the sides, but during rush hour there is no parking. I was riding home during rush hour yesterday, staying in the right lane at about the right tire tread (3-4 feet from curb). Most people will switch lanes to pass me. Some will go mostly into the left lane. This doesn't bother me too much, as there is still usually at least 5 feet between my bike and the car passing me.
Last night a woman woman in a big Explorer passed me with about 1 foot of clearance. I slapped her rear quarter panel as she went by. I wasn't angry, I didn't flip her off, and I didn't chase her down or anything (I've done that before, and decided it was pretty stupid). I just wanted her to know that... I don't know. What did I want her to know? She must've known I was there; it was daylight, I was wearing a white jacket. I suppose I wanted her to know that her passing me wasn't very safe. I don't know if it effectively communicated that, but I hope she at least thought about it. "Why did that guy slap my car?" Perhaps she will just determine that I'm an idiot, but perhaps she will examine her driving technique and find it lacking.
So... should I refrain from doing this in the future?