Do you mean an adult who is all about some team that they worship like the Atlanta Falcons. Nothing quite as pathetic as someone over 4 that says "we" when speaking about what their favorite team did in the "big game" today, like they are some how part of the team instead of couch watchers rooting for their boys. Of all the "who gives a shits", team sports takes the cake.
That's just my opinion, if you want to paint your car your team colors and act like a fool for them I'm sure they really appreciate the support and don't make fun of you in the locker room(sure they don't)..... after all, they are the ones taking the hits and making most of the money.
Too bad there isn't a smiley performing oral on a football smiley, it would seem so apropos for you.