I once had a bag of nuts with the warning: "If salted, contains salt."

Many years ago, the office I worked in bought a microfilm reader. We opened the carton, gingerly removed various delicate-looking components and spread them on a table, and then, at the bottom of the box, found a list of Instructions for Unpacking. The first instruction was to turn the carton upside down and open the bottom. There were no such instructions on the outside of the carton. The Silly Sixties evidently infected even Eastman Kodak!