Pocker Pal
If you play harp, you carry one in your pocket.
Pocket lint does a number on reeds, so make sure to turn out your pocket and give a good shake before putting your harp in. Hohner used to make a thin vinyl case for their Blues Harp model and it was perfect for protecting the harp and not taking any extra room in your bulging pocket... eBay anyone?
Hohner's new formed cloth case with zipper for the Marine Band Crossover (same as the case Bends uses... harmonica manufacturer in Brazil) is form-fitting and smaller than a full-size case and can work.
Whether you go naked, or in a form-fitting case, please don't put your harp in your back pocket (my first harp died an early death that way).
By the way, the A Harmonica is the most common to carry in your pocket. If you're called up to play, it's assumed if you have a harp in your pocket that it's an A harp.