This picture illustrates an exchange in power.  Until you have tried this, it may seem a bit off for both a female or a male looking at it.  However, this can bring a level of understanding and closeness to your partner that you would not experience in a normal relationship. Women are far too often on the receiving end of such aggressive sex, but when you reverse this, it not only gives power to the woman, it lets a man know what it feels like to be an object purely for the woman's satisfaction.