Wasn’t it macabresoul who wanted to go postal on someone who sprayed water from their windshield wipers on his car?
A little yellow food dye added to the fluid, and the nozzle aimed over the roof should give your “friend” a little non-violent lesson.
My wife was accosted by someone in a road rage incident a couple years ago. She was on her way home from work, in a car that had engine problems. She slowed down climbing a hill, because the car was doing its best, while a pickup truck behind her was flashing its lights and revving the engine. She pulled off the road to let him pass, and he pulled over, walked over to the car, and started screaming at her. He slammed his hand on the rain guard and shattered it. She drove off withour opening her door, he jumped back in to the pickup (with a female passenger who was screaming at him) and followed her down the road. She made her way to a convenience store, and ran in to call the police. The pickup circled the parking lot and left.
My therapy for her in this case was an evening of Twisted Metal multiplayer.