If I understood well the exercise named Fowfer's or BTC (behind the cheeks stretching) is supposed to be done by sitting on our dick previouslyu stretched between the buttocks.. now my questions are: 1) where have I to place my ballsack to allow the penis to go behind till rech my buttock's crack ?? 2) have I to sit on my stretched penis and my balls?? (it sounds painful) 3) Is it worth the effort??