You know the choke: on a guillotine attempt, get side control, trap the arm with your elbow, underhook the head with your other arm, lock hands, and drive your shoulder into your opponent's neck. I use this choke a good bit, with mixed results. Like the N/S choke, it seems to me that this is a "feel choke" where minor adjustments make all the difference. Question: what are those adjustments? I was trying to teach this choke to a beginner the other day and I realized I didn't really know the answer. After I showed it to him, he rolled with another guy and applied it, but it did no good. Here are some observations, speculations about it: (1) It won't work if your opponent has your neck broken down. You need a straight neck. (2) Your shoulder has to be IN your opponent's neck. Any space will ruin the choke, and your opponent can defend with his free hand on his ear or cheek. (3) Long arms and a strength advantage help a lot. I've rarely gotten it on someone bigger or stronger than me, and if I have difficulty getting my hands together, the choke won't work. (4) A gable grip with hand underhooking the head on top of the hand trapping the elbow is the best grip. (5) Pressure from your base should be applied at about a 45 degree angle through your opponent's torso (up toward his trapped shoulder). Any corrections, additions, tips, or further speculations appreciated.