This is by far the best technique I have found!!! My wife walks on my back at least once a day and it is exhilirating!!! It sounds like someone is twisting a sheet of bubblewrap when she does it. Once she did it and she said, "Wow, that was a good one!" and I said "Oh g*d, I can't feel my legs!". She freaked out. You can also have someone press hard on your sternum. I've gotten some great pops that way.

Keep on poppin'!