OW,
I had to laugh when you threatened to "Bobby Trap" your lawn. I had the same experience years ago when in Nebraska on recruiting duty. I lived on a corner lot and had a fairly good sized corner which one little pre-ick decided he would be funny and cut across my lawn "CONTINUOSLY"! So I decided to bury some axles out of some of my old cars, actually I drove them in the ground about 3' and turd boy hit three of them and proceeded to put a hole in his oil pan, tranny pan, and well as dislodge his rear axle.
See the problem was I could never catch him "In the Act" as the cops put it and even though the tracks let straight to his house I had no recourse. So this time the oil laid the path for me. His daddy couldn't get him out of this one. When questioned about the axles I stated I had them in the ground to hold my animal while aways from the house. Don't know what it cost him but he didn't drive through my yard again!!

Trumpy