Ok you have achievement's like Alterac Valley All-Star Alterac Valley All-Star - Achievement - World of Warcraft
or Stormy Assasin Stormy Assassin - Achievement - World of Warcraft
Anyway achievements you can only complete while in 1 (Boss)Fight/Battleground.
What this exploid does is it lets you continue your achievement even when your bg/fight is actualy over (Normaly the subachievement reset when you leave or end a bg.) Here come's the exploid:
If you for instance want Alterac Valley All-Star:
1. You sign for av.
2. The message box pop's up.
3. You join 2 other battleground's BEFORE going into AV.
4. You join av and try to do as much as the achievement when you can.
5. A messagebox pops up for another bg
6. You join the other battleground.
Now the subachievements did NOT reset while you LEFT AV. So the next Alterac Valley you join you will still have have subachievements. (a subachievement in this case would be Assault a graveyard etc).
I checked forum, this is NOT a repost. And it is a terrific way to get all the achievements you would normaly need to do in one fight. THis also works on boss fight's but you would need to have a message box pop up for a bg and use something like invisability and then you can accept it.