I've got a neighbor with an alarm on his car. It doesn't appear to have a sound system in it, but it has an alarm nonetheless. The alarm has a very sensative shock sensor which goes off with some frequency. Every car that goes by with a stereo going sets it off. Every thunderstorm sets it off. That is annoying in and of itself. But the worst part is, my neighbor makes ZERO effort to silence it. I don't talk to this neighbor that often as all... just another random renter who really doesn't care. But I did mention it in passing to him once and he said he would see what he could do. He's done nothing.
What I would like to do is make a device that will generate inaudible, low frequency cannon of sorts that can focus a beam of shock at his car to set of his alarm whenever I want, so maybe it will get his attention finally. Like repeatedly at 4AM.
I am going to hit up google too... but wanted to see if anyone had any ideas here first. $50 or less would be great.