When I was a kid, my town had a bowling ball factory where they would leave the rejected balls in a big pile in back of the building, unguarded. In winter, we would sometimes nick a few and walk to one of the bridges on the local river which had iced over and drop the balls in. Dropping little rocks into water is cool and all, but absolutely nothing compares to the satisfying explosion from one of those bowling balls on ice.
Well, this was the late '70s when all kinds of crazy shit was going on that's unheard of today. As another example, retail stores used to just leave handheld electronic games out on the sales counters where amoral young boys could easily slip them into their paper bags and stroll out the door with them and then tell their parents they'd "found them in the garbage". Not that I would know anything about that kind of thing ...