In my previous incarnation, I worked for an airline that did quite a number of flights to "holiday" destinations. The number of pax (male in this case) who would board the return flight in vest (singlet to our colonial cousins) and shorts, plonking his bod down next to some more civilised passenger. I made the suggestion that at least a short-sleeved T shirt would be mandatory, and suggested that the company had a supply available. My idea was to have the slogan "I am an idiot" front and back. It was never adopted, but I still think it's a good idea.