Anyone who makes an attempt to emulate another person/subculture/lifestyle; usually done to look cool, make friends, or to get attention. More often than not a wannabe is either insecure and wants to find their niche in society or they are just craving attention. These groups include "prep", "gangsta", "goth", "emo", "nerd", and "redneck" ("goth" and "emo" being the most popular). It all starts out when the wannabe sees a certain group as cool and then they try to adopt the style/attitude/musical taste of that group. This normally results in ridicule and the disgust of the people they try to be like.
For starters, whoever posted entry #10 here. I think I know who you are and the person you are talking about... thats not a very nice thing to say about one of your fellow bandmates, now is it?
Seth (emo): Hey... you know that Jacob kid, right?
Henry (another emo): Yeah what about him?
Seth: Well.. he kept staring at me all week last week and today at school he had the same shoes as yours and the same haircut I have.. and he keeps trying to talk to me about how cool Hawthorne Heights and MCR are.