This has been said at last 20 times now, but Shorty looks like he might've had some recurring priapism (prolonged & painful erections) in his youth. This has been known to cause permanent enlargement, particularly with regard to girth.
Many black Americans (West African ancestry) have a single copy of the "sickle-cell" trait. Instead of having full-blown sickle-cell disease, people with one copy's red blood cells only form a "sickle" shape when they're sick or in distress. This was a protective mechanism in West Africa where malaria was abundant and the "sickling" during the infection helped people survive the illness. In any case, there are rare occasions where the blood cells "sickle" in the penis doing erection and can lead to priapism. Here's a case of a man with a whopping 63 episodes of priapism related to sickle cell disease:
An unusual case of priapism.. His penis was not damaged, but rather "hypertrophied". Similar case studies exist, with potency remaining intact and a notable enlargement of the penis, particularly with regard to girth.
Note* Just because West African blacks are far more likely to have this happen does NOT mean that it's common at all or that blacks are bigger. It's EXTREMELY rare. The trait has to be activated due to extreme stress, and it's quite rare for even this to lead to priapism which is a medical emergency. There's no convincing evidence that suggests black and white men are different sizes.