'scuse me, but i'm clueless

What the heck is a BNF? A secret regime in the SV fandom? Are these the elite? I'm just curious, and confuzzled, because reading posts that mention BNF's is like trying to decipher coded messages (which are quite amusing, nonetheless - from what I do understand.) You'll have to pardon my ignorance - I'm like a hermit, I am. *nods*