It's a popular bit of Rock & Roll lore: The band Van Halen conducted a test to make sure its tour contracts were being read, placing in a line saying there were to be no brown M&Ms backstage. Not surprisingly, they found a couple browns and trashed their dressing room in response. 

Van Halen was the first band to take huge productions into tertiary, third-level markets. We'd pull up with nine eighteen-wheeler trucks, full of gear, where the standard was three trucks, max. And there were many, many technical errors -- whether it was the girders couldn't support the weight, or the flooring would sink in, or the doors weren't big enough to move the gear through.The contract rider read like a version of the Chinese Yellow Pages because there was so much equipment, and so many human beings to make it function. So just as a little test, in the technical aspect of the rider, it would say "Article 148: There will be fifteen amperage voltage sockets at twenty-foot spaces, evenly, providing nineteen amperes . . ." This kind of thing. And article number 126, in the middle of nowhere, was: "There will be no brown M&M's in the backstage area, upon pain of forfeiture of the show, with full compensation."

So, when I would walk backstage, if I saw a brown M&M in that bowl . . . well, line-check the entire production. Guaranteed you're going to arrive at a technical error. They didn't read the contract. Guaranteed you'd run into a problem. Sometimes it would threaten to just destroy the whole show. Something like, literally, life-threatening.

For those in security, there's a valuable lesson here. Large enterprises are constantly circulating thick stacks of to-do and not-to-do lists, directions on how to proceed, and so on. The smartest and most dedicated people are still human, prone to skimming a line here or a page there. But doing so can compromise an organization's physical and online security.