Mr. Sonny Hughes has been training since the late 1950's. He has trained under Gene Lebell, works closely with the LAPD and other various police agencies, and is a specialist in Close Quarter Battle (CQB). Mr Hughes has been kind enough to share his techniques with us.
This submission is a painful option from the up down position in your opponent's guard. However you decide to get here, play around with it. It is not the most sneaky move, but it is ridiculously painful.
From the standing position in his opponent's guard, Sonny turns sideways and shoves his right foot under his opponent's butt. Notice that Sonny's feet line up in an "L" shape.
Sonny reaches his right hand between his legs and pulls his opponent's left foot through while using his other hand to hold their right foot.
Sonny squats slightly and forces his opponent's left ankle onto the thigh of his opponents straight leg. As he does this, he starts to lean away from his opponent.
While keeping the straight leg tucked under his arm, Sonny tries to straighten his own right leg into his opponent's bent leg. This puts pressure on both the ankle and the knee.