Someone I know has come up with this prank / revenge idea: you create and print out a parking ticket, making it look as official and as confusing as possible. Avoid mentioning names of any official and governmental institutions though, so that you cannot be accused of impersonating them if the prank gets traced back to you. Put in a huge fine, something like $468.45 in there, but give no directions as to how to pay it and no contact info. Stick it to the enemy's windshield and watch them panic. :) It might take a while for them to figure out that the ticket is fake. :) :)