I'll copy and paste the answer here:
Stan 58 up, 9 down
Stan as many people know is a character in Eminem's popular song Stan. Because the character was so obsessive the name can be used as an adjective. You could call somebody a "stan" if you think they are obsessive of someone or something. One good exampe would be in the song Ether by Nas.
You a fan, a phony, a fake, a pussy, a Stan - Nas
This was the shortest most accurate one from urban dictionary. Still amazed I've gotta post this. Cultural differences arts crafts fgts blah blah bloop!