the 10,000 kills achevement in gears of war can be quite daunghting to most people, but not anymore! all you need to unlock these sort of achevements is some that has got the achevement legit and you trust. heres how:
note: make sure if u are giving someone your account (so they can exploit this glitch) you trust them, or you might never see your account again!
recover someones account that has gotten the achivement LEGIT!
Once you have the other account, set it to Auto sign in. And switch yours to not auto sign in.
Next, turn off your 360, then turn it back on. Now right when the game starts to load, press the menu button.
Once in the menu highlight your name so your ready to press a to sign in.
Now right when it shows the other persons backround/ Theme appear, then quickly press A to sign into yours.
Now you will know when you got it because you will either have no messages or no friends. Now just join a ranked game and get a points, or a kill and you got it.
This will also work with other achievements as well, such as the 'best of the best' achivement in 'rainbow six' and mostly all games wit a "get X amout of kills(with X weapon)"
this glitch is most commonly used for the 'seriously' achevement in gears of war,
here is a vidio of the glitch in action.