Solution to car alarm problem

Ingredients:
  • 1 brick
  • 1 piece paper
  • 1 pen
Directions:
  1. Using pen, write "Next time, it goes through the window," on paper.
  2. Bring paper to offending car and place above driver's door.
  3. Set brick on top of paper.
  4. Leave.
No one gets hurt, no property is damaged, and you can be damn sure the owner is going to do something to fix the problem. Plus I think it's pretty funny. Feel free to use your own creative messages.

(this writeup was moved from The Car Alarm Problem, and how to solve it)