A fun choke from the Turtle Position. I learned this as a blue belt and then made it my goal to get it in live rolling because I thought it was the coolest thing I had ever seen. Sadly it took me almost 3 months to get it because our instructor yelled at us if we tried to rest in the Turtle position.
The best time to use this is if your opponent tries to rest in Turtle or they actually play from the turtle position.
Be careful when going for this that you do no kick your partner in the back of the head while swinging your leg around. To avoid this make sure you really stand up and disengage.
Because you disengage for this move, you may be letting your opponent back into the game. It is for this reason that I do not use this move often.
You may feel inclined to practice this move slowly but the momentum of this move makes it much easier. You will find that after you get the movement down it is amazingly easy.