I have found an exercise that claims to increase girth hugely but it is preformed on an erect penis and I have not heard of it anywhere else so was wondering if it was dangerous. I have described it below
Grasp your penis at the base with thumb and first finger as far into your body as possible. Kegal hard and then squeeze so that blood is forced up the shaft and your penis is fully engorged (the veins along your penis will be bulging and the head will actually look glossy when done correctly).
Hold this position for a count of 30. You can move your hand forward up to an inch to increase pressure while you count. After 30 seconds release your grip and shake out your penis for a few seconds. Then achieve another full erection and repeat.
If you have heard of it and have tried it please tell me if it is any good and what part of the penis in particular it enlarges.