Are you a freelance pirate hunter that ended up neutral to the Rogues for shooting a bunch of Xenos? Or perhaps the Corsairs have forgotten that you killed a few of their friends because you got swarmed by Daggers in Liberty? Bribed the Junkers, but the Hessians are still supposed to want you seperated from your cargo?
/hostile!
/hostile <faction> sets the faction to full-red hostile without affecting any other rep. Perfect for minor repfixing and practically impossible to abuse.
At least, as far as I can tell.
And there's more to it than making NPCs shoot you - it's also helpful as a quick indicator of whether or not the player in front of you might try to kill you. (hint: he will.)