I was introduced to this by Jon Nash, he did it on Danes Jeep years ago. We were just hanging out at the Gap parking
lot and Dane left his car there. Jon had some ketchup packets and he told me about this great sabotage. What you
do is squeeze out the ketchup right above their windshield wipers so when they use them they smear ketchup all over their
windshield. For immediate results you have to put some kind of stain on their windshield so that they'll use their wipers.
Voila! An easy way to ruin someone's day.