This could be a common sense. But anyways, here it goes.
1. From the start of week (raid-reset WoW-vise), go into every ICC10/25 avaible.
2. Slay the first trash mobs before Marrowgar. You could even AFK the whole time. Slay 1-2 mobs, then say: "brb sec". They won't probably notice you until the boss. Leave raid when they approach boss. Or just Alt-F4, so you don't get flamed.
3. Go into another raid. And so on, getting around 1000 rep per 20-25 mins.
4. ???
5. PROFIT.