Putting the Fear into Small Children

For awhile now we have had this problem with the neighborhood children throwing the rocks in our driveway. Well it got to the point where I would wait for them to come home from school and as soon as they picked up some rocks I would throw open the window and tell them to stop. I did it a few times before I got really tired of it all and about two weeks ago I rationalized with the kids. I told them that the neighborhood association was about to start charging their parents and the cops may be getting involved. Well that seems to have worked. And not only did it get them to stop, but I saw the kids kicking the rocks BACK into our driveway on their way home. I should ditch preservation and go into child psychology or hostage negotiation.