Approach your opponent from behind.
Take your dominant arm and wrap it around the neck of your opponent. Your bicep should be pressed against one side of the neck and your forearm should be pressed against the other side. Apply pressure to both sides of the neck by squeezing your forearm and bicep together.
Grab the bicep of your free arm with your dominant hand. Use your other hand to press the opponent's head forward toward the elbow of your dominant arm. Keep in mind that your opponent will not be able to breathe if this move is being properly applied.
Immediately relax your hold when your opponent goes limp, but do not unlock your arms. You must relax your hold enough to allow your opponent to breathe again, otherwise you could cause brain damage or death to your opponent. Keeping your arms in place will ensure your control over your opponent if he wakes up quickly.