A guerrilla promotion to promote the Nissan Altima's push-button ignition begins this week. True Agency will deliberately "lose" 20,000 key rings in bars, concert halls, sports arenas and other public places in seven major markets, writes the New York Times.

Each key ring will have a unique code, giving finders the chance to enter a sweepstakes either by sending text messages or visiting a website, which is to be available this week.

A tag on the key ring declares, "If found, please do not return," because the Altima "has Intelligent Key with push-button ignition, and I no longer need these"; the reference is to the technology that allows an Altima owner to start the car by pressing a button on the dash rather than inserting a key.

The budget for the promo is estimated at a modest $100,000, which includes buying 60,000 keys and 40,000 tags and paying for the sweepstakes prizes.