No, I did not mistake this for the Penthouse forum.
In my grappling class last night, I was whining *ahem* asking my instructor about G'n'P defenses, as I got smeared in the first MMA sparing session I attended.
My problem was the opponent acheiving full mount and pounding me. Heretofore, my escape training did not account for someone punching me at the same time.
So, we worked a couple of defenses that provided for the opponent hitting me whislt I try to escape.
"Vibrating" was one of the things he showed me. He learned it from a Larry Hartsell seminar. It is basically rapid-fire, non-stop bucking with the hips to unbalance the opponent.
I found this quite effective. I was able to unbalance my 250lb instructer (I am about 170lb), and keep him from hitting me even before he got thrown off.
Not sure if this is common in BJJ, but figured I would pass on an interesting experience.