I never really did understand that, I think one person somewheres did it, then some people followed. To me it just makes the person look like an idiot when their hat is cocked to one side. I wear a hat to keep lighting out of my eye, so the bill forward is how I wear it, now on the other hand, if i'm riding in a convertible car or a t-top car, or on a motorcycle, I turn my hat backwards so the wind doesn't catch the bill of the cat and yank it off. Plus a hat isn't comfortable turned to either side, because of its shape.