I taught the Sneaky Choke from 3/4 mount a few videos ago and it was very popular. It's a position, and submission that I use frequently.
Some people asked questions as to how to deal with your opponent who "answers the telephone" or defends by bringing their hand to their ear.
In this video I show a great response to that question/problem, the one handed Darce.
I showed something very similar to this from Butterfly Guard but you will find it much easier to finish this as it's shown in the video.
One of the things you need to always keep in mind is maintaining your base. Any time you're going to choke using the setup hand as a cross collar you have to be weary that your opponent may try to roll you over...so maintain that base.
Once you have your base in check you can think about feeding your bicep to the back of your opponent's tricep. Reference the video to see what I'm talking about. Realize the VERY important difference in putting your bicep on the back of the tricep and pulling the elbow across. If you try to pull their elbow you're going to have a rough time because they have a lot of bone support with the elbow in tight.
Once you get the bicep in place you should be able to finish by applying pressure with the shoulder/bicep into the back of your opponent's shoulder/tricep. This will feel a lot like a one handed Darce.
Keep in mind this works well because of how deep your setup hand is. If you had a normal grip this would not be possible, but that sneaky choke grip that you get from feeding your fingers behind the head is more powerful than most people realize.