1. Thank the topic also rep ( I WILL CHECK )
2. Post your gamertag, then wait for an invite may take bout 1-5 min
3. Join the invite, then back out fast.
4. Go into split screen with the checkerboard map, and start it. Hit the back button, then what ever you want.

Back button= Rank 55
Dpad Right= 0 prestige.
Right Stick= 1st prestige.
Left Bumper= 2nd prestige.
Y Button= 3rd prestige.
RT= 4th prestige.
LT= 5th prestige.
Left Stick= 6th prestige.
X Button= 7th prestige.
B Button= 8th prestige.
Dpad down= 9th prestige.
Dpad up= 10th prestige.
Dpad left= 11th prestige.
Look at the ground= Unlock all