I've heard some movie theaters have a device that block's cell phone signals.?

[silver lining]

so movie goers are not disturbed by incoming phone call's. if this is true, is their a device I can buy and stick on my car so people who are driving, say within 500 ft. of me will have their cell phone signal disrupted so they have to concentrate on driving and not talking. I know your going to say they will concentrate harder on making that call, but sooner or later they will discover the phone dosent work and give up. is their such a device???????????