So you don't know what a shnoon is?
I was "exp" banned for playing 5 games with some friends trying to get achievements. My question is, why even make the achievements available in social if you don't want friends to play together and get them? Ive read these 4 reasons why you would get banned:
Manipulating network conditions to give yourself an advantage, or to the detriment of the experience for other players.
Modifying your Xbox 360 hardware or Halo 3 software in any way.
Skill or XP Boosting, deleveling, cheating or any other type of unsociable and unsportsmanlike behavior.
Impersonating a Bungie employee on Xbox LIVE with intent to defraud or cause harm to other players.
and my situation doesn't fall under any of them. Honestly, there was absolutely no boosting involved, considering I only won 2 of the 5 games(woot, 2 exp). Also, many other games have similar achievements in multiplayer, and they don't ban people for working together to get them. If they were so worried about that, they'd make them for RANKED ONLY.