when you feel compelled to vent your spleen at somebody, ... regardless of the actual reason.
I was parked on the footpath which is part of a 5 car driveway mind you ... waiting for my kids to jump in the car ... left about half the foot path easily accessible ... but an old coot and a roadie, had to press his brakes and slow from 15kph to 12kph* for 2.5meters ... and he felt compelled to give me the evil eye and yell shizzle.
Anyway, I vented my spleen back and my 5yo looked at me and asked, "why did you scream that for dad" ... :wacko:
* actual numbers may vary