a TRUE green day fan- A perosn who has listened to Dookie at least and their other albums. If you have only listened to American Idiot, then you are not a true fan. You can't just say you are a fan and you have only listned to one album. And you at least have to know three of the bandmembers names and some info. How hard is that? There are only three members! And if you listen to a song, such as American Idiot or Longview, I don't think you should just say you like the song because it's catchy or whatever. All of their lyrics means something and you should pay attention to that. That is one of the main reasons I luv them! Their lyrics are really powerfull and mean a lot. So that is my opinion of a true green day fan pretty much.
To be a TRUE green day fan, you must listen to lots of their albums and other stuff.