Not a True Fan
Active: an insult when calling bullshit about a level of fandom, used to call out a poser/noob/rookie/padawan
Passive: a point of preference to indicate you don't really like something
Customer: Sure I like Star Trek. Boba Fett is my favorite character.
Comic Shop Clerk: N.A.T.F.! (while pointing)
Guy who's Music taste you used to respect: Hey man, Pearl Jam is coming to town soon, wanna get tickets?
You: Meh, N.A.T.F.