I don't know a single person from my entire life that ever got a black eye that was not from a fist fight (and even that number I can count on 1 hand)

Likewise. Their black eye club definitely does make it look suspicious. Just not normal. And if they all are that prone to stumbling and getting shiners, why not equally many times when one of them would have had nice bruises on some other part of their face, showing it off?

It is rather easier, after all, to get hit everywhere else but your eye as most of us kind of automatically try to protect those. I have hit both my forehead and my nose, and once the left side of my jaw, badly enough to have a bruise there when I stumbled with something like a car door, or a fridge door, but never my eye.