B.Y.O.F.S or Bring Your Own Fucking Shit is the way to respond to the office mooch when he wants to come to a party you are having.
Mooch: Dude I heard you were having a party.
You: Not really a party. Just some guys coming over to watch the game.
Mooch: Sweet I'll be there at 2.
You: Ok, but just so you know its B.Y.O.F.S. cause I'm not buying any shit for you!