Let's see...
Here in Japan:
I slapped the trunk of the taxi that buzzed me, cut me off, and then slowed down right in front of me.
I've gobbed a few cars that behaved dangerously/illegally towards me.
The one time I really, really wanted to punch somebody was when a van driver broadsided me and knocked me down. He got out and stood beside me while I spent about 3 minutes carefully examining the damage to my bike, which I did to distract myself from an intense desire to smash him to a pulp. I was amazed at my own anger-management and self-control.
In the US:
Once, a long time ago, while a Pittsburgh police officer was straddling my front wheel while holding onto my handlebar and shaking my bike and spitting threats in my face, I briefly considered reaching down and un-clipping my Kryptonite U-lock and roundhousing him with it... but a sudden vision of being stomped into the asphalt by 10 or 12 cops made me reconsider.
Guess I'm not as violently-inclined as my fantasies would have me believe.
