Gentiv Ultra I'm going to introduce a mechanical model to help explain things. Think of one of those hot-dog balloons. You know, those long skinny balloons. Imagine filling that balloon up to its normal capacity using helium. Then, tie up the end so the helium won't leak out. Then take the "nipple" of the balloon (the end part that is tied up) and attach it to the wall with a thumbtack. The balloon represents your penis. The wall represents your pelvic girdle (where your penis is attached). The nipple (the tied up bit at the end) represents your penile ligaments.