Having started the thread, I must confess to wearing a Vote for Cthulhu tee shirt at times. Also, I used to wear to matches a MoMA ball cap. It was to see who had some culture (Museum of Modern Art). I used to wear a Rangemaster tee shirt to the school gym. It was rather explicitly firearm-ish. Probably get me reported if I still worked there. Now I wear a university shirt to the local gym.
Had a nice KRtraining dress shirt, that I would wear to work. When asked what it meant, I said, high level executive training seminars.
Car just has a university logo sticker.