The security company ADT wanted to convince apartment and condo owners in Santiago, Chile that it's really easy to break into their homes. So the ad agency DDB made spring-loaded boxes and shoved them under the front doors of prospective customers. At the link, you can see a video from the ad agency showing how they work.
Link via Geekosystem | Photo: Copyranter
People get it. But it's no fun if everyone comments 'oh yeah, advertising, neat'.
The company isn't trying to fool you into thinking they actually broke into your house-- they're trying to get your attention. Once people examine how the box works, they'll get the gimmick. And most importantly, from an advertising perspective, people WILL examine the box. This is one piece of junk mail people would actually take the time to read, instead of immediately discard.