Overshirts are just about the most casual outerwear there is, ranking alongside trucker jackets, field jackets, bombers, and double riders (although they're each casual in different ways). Also referred to as "shirt jackets," overshirts are basically shirts designed to be worn over other garments--not, as Jordan Petetson's tailor suggests in the original video, jackets to be worn over a shirt. Any jacket can be worn over a shirt. Men use overshirts in the same way they wear a flannel over a tee shirt, except that the overshirt is a little thicker and warmer and usually has a little more room so you can layer it with a hoodie, too. You *can* wear it over a collared shirt, but they're usually not designed to be worn like that, and the collar clash usually just isn't the vibe, as you see in the video. There are dozens of other casual jacket styles thar are easier to dress up. Even a blouson with a spread collar just looks better dressed up than overshirts, because they're designed to f...