Car alarms are a joke around here; no one bothers to look when one goes off.
However, an Engineering professor at the college where I attend classes had an interesting idea...and it works.
Somehow or other, he wired up the doors of his car to electrify when the car doors were locked. I can't remember how much of a jolt he used, but I do know that while it wasn't a dangerous amount, it was enough to make someone think twice about touching the car.
He still has it that way, as far as I know, because he has a little sign in both the driver's side and passenger's side windows proclaiming the car to be "electrified - please do not touch."
