I repeat this so often, it's like spam.
Don't use standard physicological or metaphysical curse words. If you want to yell a curse at a deserving driver? Call him a drunkard.
"You D**k" isn't nearly as effective as "You DRUNK!"
Could you imagine, if law enforcement was forced to intervene, his distress at having to tell the officer that you called him a drunk? "Sir, would you care to discuss that before, or after, the breath test?"
He was a jerk. He was in a really dumb vehicle. He was harassing a cyclist. Just what do you suppose the chances of him being over the legal blood alcohol content are?
Call him on it.
I'm thinking it meets the preponderance of evidence criteria, even thouh it's far short of "beyond a reasonable doubt".
Sure, if you shout it at every damn jerk driver, you might be wrong once in while. So what? "If you don't want to be called a drunk, stop driving like one!"
If you are going to shout insults? Shout the appropriate one. "DRUNKARD ! ! !"
(Also, I have seen people straighten their behavior right up when I shout this.)
Mick