LMAO, a lot of these are really good! I especially liked FFM's. We saved all the 6 pack rings from soda at the pizza shop for over a year, then tied up a coworkers car in much the same fashion.
Another great one was an 80 pound pile of fresh pizza dough dumped off on the owner's son's porch. (college student at the time). No one realized at the time that he was going to be gone for the weekend. Do you have any idea how many times 80 pounds of dough doubles in size during the course of a really hot weekend? His porch was a giant doughball, covered in ants when he returned.
btw, the OP's prank isn't a prank. It's just plain theft. Funny how some people don't recognize the difference. It's no different than shoplifting, and I've never seen any reasonable adult consider shoplifting as a "prank."