Rear Naked Choke. Chokes are the most effective method of disabling an enemy.
This technique should only be executed from the back mount after both leg hooks
are in place.
(1) Step 1. Leaving the weak hand in place, the fighter reaches around the
enemy’s neck and under his chin with the strong hand.

Rear Naked Choke
(2) Step 2. The fighter now places the biceps of the weak hand under the
strong hand, moves the weak hand to the back of the enemy’s head, and completes
the choke by expanding his chest.

Rear Naked Choke, Step 2