A few rules so this is playable. I've adapted these from the rules posted at South Paranoia. Some of the rules are copied directly, and some are changed quite a bit.
1) Tell your parents/roomates that you're in the game if they're not participating (assuming you don't live on your own).
2) One dart / one kill. Unloading your clip is badass though, but risk it at your own peril! Kills should be carried out away from the public, but there's no reason to keep them secret from other players. Public kills still count, but it's hardly in the spirit of a "secret nerf mafia war".
3) The object of the game is to be the last team standing. Teams and players will be ranked by points for good kills/deaths.
4) Places of business are off limits unless a player announces publicly that it's cool. Same with school. It's just a game, and we don't need anyone getting in trouble.
5) Off-brand Nerf guns are cool, but no airsoft or paintball. Modded nerf guns are encouraged because they're cool.
6) If there is an argument over whether someone has been assassinated, the shooter has the final word. HONESTY is essential to this game. Also, points will be awarded for video evidence of a hit so that all may enjoy. Points for a well played death will be awarded to the victim's team.
8) Anything you are wearing or carrying on you counts as part of your body when you are being shot. This means that if you are holding a backpack and get it gets shot, you are dead. This also prohibits the use of shields. You may not block any bullets, and if you are also killed if your gun is hit.
10) You may not shoot or be shot while naked.
13) Shootings can happen in the home, but don't break any laws. Camping outside the house, using a ruse to gain access or pulling a Terminator style kill at the door are all pretty boss ways to take someone out.
14) No stealing of weapons or paraphenalia from anyone's arsenal.
15) You can be hit while in your car, but simply hitting the exterior of the car and not the person does not count as a kill. A shot fired at a person operating a moving vehicle will cost points to the team and could result in elimination FOR THE ENTIRE TEAM because that shit isn't cool. Likewise, drivers operating a moving vehicle will cost their team points or have their team eliminated by firing during a drive by. Watch the road, your passengers can handle the car. A rocket successfully fired at a car, or a sock grenade dropped in a car, results in a kill against everyone in the car.