On a serious note, I always wear a fitted whenever I'm wearing something navy, red, white, or something that doesn't look stupid with a navy hat, and I have many shirts and jerseys. I don't wear them out to parties or anything, but I usually put one on when watching games, or otherwise I'll just wear them around or to class or something.
I even have quite a collection which have no sleeves; they're all older and too big though from when I was heavier, so I just wear those shirts to the gym, they're perfect for that.