Ayanami Rei's Journal: Diabolical ways of getting rid of vehicles?

I've got this problem. It seems that the whole world has taken it upon themselves to use the shoulder outside my development as a place to sell cars. They sit parked near an intersection with for sale signs within. I used to call them up (phone number on for-sale sign) and politely tell them that I would have their car towed and/or ticketed within a few hours if they didn't haul ass.

I got tired of that. There's 3 out there right now, I can see em too from my window.

So the question is, does anyone have any creative ways I could make their lives miserable? I have considered using brightly colored posterboard and duct tape to cover the signs and attract the attention of cops (maybe scribbling "FUCK YOU COPPERS" or "TOW ME PLEASE" in marker on it would help)

Comments?