So let me tell you about Mark, my friend, co-worker and supervisor.
Living close enough to work, he eschews buying a parking permit, choosing instead to walk. Normally this works out well, save for inclement weather.
One issue, though, is that shoes one walks in are not the best shoes to wear with dressy clothes. Having to deal with administration and committees means that Mark has to look nice (unlike slacker programmers like myself, who do not venture out of our holes). This leads to Mark keeping a pair of shiny dress shoes at the office and doing the "Mr. Rogers" thing when he arrives for work.
Well, we're moving offices, and found ourselves doing hard labor. Mark found that though the jeans and t-shirt he wore were adequate for work, the sandals that he came to work in were not. Thus, there was only one option.
So here it is, the new fashion craze. Rolled up jeans with shiny black dress shoes. When all the cool kids are doing it, you'll know where you saw it first.