WNBC ("Wearing Nothing But Chainmail") is an acronym mostly used by geeks (aspecially Dungeons and Dragons geeks) over IRC and other on-line chat methods, in order to arouse sexual attraction among the significant other.
Alice: Hei bob.
Bob: Hi Alice, how r u? everything is kewl?
Alice: Oh yeah... WNBC ;-)
Bob: O boy, it's getting hot in here!