Check out this Superman choke by BJJ black belt Ronald Manipol , a student of Carlos Machado in Dallas, Texas. It’s called Superman choke because you literally look like a flying Superman when you are applying it.
This is works particularly well when the opponent is defending your regular sleeve choke from the back. You then climb your hips up all the way behind their shoulders and hip in, stretching your body and applying the choke.
You really need to put pressure with your hip going forward. The amount of pressure is insane. Try it out.
Jean Jacques Machado teaches another version of the Superman choke, this time from the turtle: