Friend of mine had a problem where kids where driving on the grass tearing it up. It kept happening. So what they did was pounded pipes into the ground and at night they would put re bar in the pipe so it would stick out of the ground. Well eventually the kids came back, drove over the re bar, and it torn up the oil pan and exhaust under his car and his car stopped running down the street. Then they called the cops but pulled the re bar out of the ground before they showed up. The kid was busted by the cops and with his car all tore up. Needless to say they didn't come back.