3M Security Glass Ad
3M was so sure their Security Glass was unbreakable, they placed 3 million dollars of cash between panes of transit glass treated with a shatter-resistant coating. Only $500 of real currency stacked on top of fake money.
People could only use their feet to break it. A security guard was nearby to make sure no one broke the rules and that people couldn't get to keep the money if they broke it.
Source: gizmodo.comAdded: 12 August 2011