It is simply deplorable that the prostate gland is so close to the urinary system that (the common) enlargement of the former impinges awkwardly on the latter. In addition, as human testicles descended -- both in evolution and in embryology -- the vas deferens (which carries sperm) became looped around the ureter (which carries urine from kidneys to bladder), resulting in an altogether illogical arrangement that would never have occurred if, like a minimally competent designer, natural selection could have anticipated the situation.
There's much more that the supposed designer botched: ill-constructed knee joints that wear out, a lower back that's prone to pain, an inverted exit of the optic nerve via the retina, resulting in a blind spot. And what about the theological implications? If God is the designer, and we are created in his image, does that mean he has back problems, too?
The point is that these and other incongruities testify to the contingent, unplanned, entirely natural nature of natural selection. We are profoundly imperfect, cobbled together rather then designed. And in these imperfections reside some of the best arguments for our equally profound natural-ness.