I've only tested this a few times so far and it's worked every time.
Supposedly they put in a fix that stops you from getting a deserter de buff if you disconnect during a battlegrounds. You can use this to cheat the de buff by 10 minutes.
Say you're in AV or a WSG that's going nowhere and you want to get out asap, but don't want to wait the full 15 minutes after you /afk. Here’s what you do:
Press alt+F4 to close your game.
Wait 5 minutes until you would normally AFK out if you were still logged in.
After 5 minutes passes, re log and you will be out of the battleground and won't have the 15 minute de buff.
Now you can re queue for what ever else you wanted 10 minutes earlier than if you were to just /afk out like normal.