Same here. Apparently I belong to a couple of NPC sororities that were never on my campus ...
:P I just de-tag myself. If the person who tagged me is a GCer, I also shoot her a message that I'm an AEPhi, not an XYZ.
My FB avatar is not a picture of me, as I do use my account for gaming. Some asshole told me a while back that my av made me look like I was 50 (not that he had HIS face up as his av... chickenshit... and btw I still get carded... but I digress) so I use a favorite stuffed kitty as my av. If my cat adoption goes through, the new kitty will likely be my new av if I can get her to hold still long enough for a pic. (I'm thinking bright light, a wide-open aperture, and some tuna will do the trick.) The only potential obstacle to the cat adoption is my husband's allergies ... in which case I'll just have to rehome him <evil grin>