I have these sensations regularly, usually a couple of times a week during the night. In my case the feeling or tingle often begins in the toes and works its way up. The genital area is usually tingling within moments. I think its simply your body wanting to "play".

Once you've learned about how to achieve these orgasms through Jack's technique I believe it becomes a learned habit, much like learning to ride a bicycle. The "body" doesn't forget it.

FlArkie