If you look to the left, above your avatar (picture) it says something like "Mouseketeer." On this board are tag fairies who may decide they like something in one of your posts and they will "tag" you - they will put a little saying above your avatar. It is totally random, and from what I understand from other posts, they do not respond kindly to begging (although I did once see someone offer them chocolate, and I'm still wondering if that worked).
You can put something there yourself if you would like, but when the tag fairies put something under there it will be in color.
Hope that helps.
MsSpinShady