Am I leaving my car parked in this spot? This should be the deciding factor for how this is handled.
This is a key point in this discussion. If I'm leaving my car, I'm much much nicer...but at the same time, the other guy should live by that same rule.
Being the parking-lot psycho that my wife claims I am, I would've probably either started yelling at the guy until one of us left, or, more likley, I would've calmly left with my wife, gone into the store, done whatever we needed to do, and returned to our car. At which point, if that guy was dumb enough to call my wife an ####### AND stayed in the parking space longer than me, he'd probably come out to a car missing at least 1 if not 2 valve stems.
You gotta have balls to start #### then leave your car there.