While a delightful existence, living on the beach in Florida (and I'm sure beaches everywhere) has its drawbacks. Among these is the short lifetime of elastic, whether on pantyhose or panties. It's exasperating to think you have a new pair of pantyhose, only to discover the elastic is gone and they're around your knees!
Another drawback is trying to tactfully remind guests that sand clings to everything and isn't pleasant for flooring. This sign is one way to get the message across.