A friend of mine posted this image up on his facebook page. Apparently if someone grabs your wrists you should break your own tailbone and the assailant will laugh so hard he will hit his head against the convenient nearby wall.
There are a lot of simpler and far more effective things you can do against a wrist grab like this. Most of these are detailed in my book, so I will not repeat them here. A technique that the above illustration does remind me of is one of my favourite sacrifice throws.
A sacrifice throw is a technique that takes you down to the ground as well as you adversary. As such, it is not the best choice if you are facing a mob of people who may be tempted to kick you if you are so cooperative to lay down near their feet. For a one to one encounter this can, however, be a useful trick to add to your toolbox.
This is a very simple technique and is somewhat easier to initiate than the better known Stomach throw (Tomoe nage). There is doubtless a Japanese term for this throw but it is easier to just think of it as the Step-Across Sacrifice Throw.
Firstly, you must have some kind of connection to your foe. Grab his shirt or he has grabbed you lapels. Hook your hands around the back of his neck. If he has your wrists as in the illustration above hook your hands outward so you do not lose contact. If your foe should release your wrists as you execute your technique you will end up on the floor with him standing over you, which is embarrassing to say the least!
Step your right foot over to the outside of his right foot (or left foot to beyond his left). The result is one of your legs crossed over the front of both of his.
Drop to the floor. You can sit down on your rear heel, drop down on one knee or just fall down, whatever suits you and the situation. The important thing is you remain in contact and the foe has to suddenly handle your entire dead weight. Executed correctly this will pull him forward, but he cannot step forward to compensate because your front leg or body is obstructing his legs. The foe is pitched forward, head first. The photo below shows a variant of this using a drop to the knee and disrupting the foe's balance to throw him to the side. The mechanisms and techniques behind this are covered in my book.
If his arms are free he may be able to arrest his fall. If he has the training and quick wits he may manage a forward breakfall or roll. Be prepared for this by regaining your feet as soon as the throw has been made so you can maintain the initiative and counter attack.
In training, be careful with this technique since it will throw a partner headfirst and they may be injured if their breakfall technique is not good. I don’t know if this throw is legal in competitions. Best consult the judges beforehand.
For information on practical self-defence techniques please by a copy of Attack, Avoid, Survive: Essential Principles of Self Defence.