I'm 22 and maybe I'll feel that way around the time I'm 30-40, but I never understood the whole analogy that you're too grown up to wear a jersey to football games. Should you be wearing jerseys all during the week while you go about your day when you aren't working? Nah.....but I can't envision myself ever not wearing a Bucs jersey on game days unless I'm out doing something else besides watching the game. It might be just me, but I don't feel like I'm supporting the team enough on Sundays if I'm just wearing a Bucs t-shirt. I have to be wearing a jersey. Wearing a football jersey and some jeans on a Sunday with your buddies isn't childish no matter what age you are....unless your wearing face paint or a matching Under Armour skin tight shirt underneath it.
I'm 31 and I work from home. On gamedays, my jersey goes on as soon as I get out of the shower and stays on until the game is over. I also live in South Carolina so the only games I get to go to are in Charlotte when we play the Panthers. I love wearing my jersey and I do it as a point of pride.