As Rob says, it's just a default message - type any number after the "f" and you'll see it.
Aside from the main five forums, there's a "7" called Extra Forum which is where announcments end up once they've been in one of the public forums and removed threads used to go there until a few years ago, and a "9" called Removed Content which does what it says on the tin.
Along with that we have a moderators area which allows us to have a conversation, view Contact Us comments and check RTPs.
