Someone suggested a concrete block wall with bushes surrounding it - I've seen many a "decorative" and/or retaining type walls on plenty of properties with many shrubs and bushes around it. If this is run over by someone in a vehicle are you telling me that the property owner is responsible for repairs to the moron's vehicle because there wasn't a sign posted that said, "dumbasses don't drive your vehicle onto my property and hit my wall"? Come on.
What you're speaking of is nothing like what was suggested.
Notice the last 2 "suggestions". Fill up a garbage can with concrete, and the "cut a hole in the bottom and throw it over to disguise the concrete post".
Both are easily proven to be done to damage trespassers and does nothing to discern between losing control of a person's car and purposefully tearing up someone's yard.
If you guys can't grasp this, keep making with the ideas. Eventually, even shmokes will get the point, but please, spare me the "a decorative bed made up of architectural block is the same as a pile of concrete disguised so as to create maximum damage to an asshat I believe is doing this on purpose". Nobody is suggesting that I agree with the idiot tearing up Chad's lawn, but stupid suggestions like those that have been given are simply nothing more than people who haven't stopped to consider the consequences of their own behavior, not to mention the asstastic look it gives to the landscape.
Rolling 4-5 large boulders onto the edge of his property does the same exact thing, and can easily be pointed to as being "decorative" and something you can easily defend. Putting a hidden pile of concrete between trees? Yeah, go right ahead and do it.
Oddly enough, I'm betting Chad gets this point while the rest of you aren't considering all the other crap that makes the news that people sue (and WIN) about, and simply think it's an airtight case that "dude shouldn't have been doin' donuts in the front lawn, yo!"