ceg1526: Yup. I trashed my lower back years ago, and as part of the rehab, I used to have to do exercises where I lay on my stomach, extended my arms and lifted them and my legs up in a Superman-flying position, so all your weight is on your abs-pelvis-dick. First time I did it, I was on a thin mat on the floor, and complained to my therapist about how much it hurt, and I wasn't talking about my back. He suggested I use a thicker mat, which was a little better.
As an aside, I once ripped my dick on the hyperextension apparatus at the gym. It's the angled one, with the two pads and the metal bar between them. Just the right space to stuff yourself into, and the metal bar had a burr on the bottom side. When you lift yourself up, my dick scraped up against the burr, leaving a prety painful scratch.
Take care
Ceg