Are you insinuating Marty needs a macro lens to see his own body parts? Don't be a size queen
But I do need a mirror to see some parts. (When I taught second level I was lying when I used to tell the kids I had eyes in the back of my head.)
And, anyway, a macro lens can take some very interesting photographs of many body parts. Such as wrinkles, hair follicles, the papillae on the surface of the tongue, the details of the iris of the eye... the list could just go on and on.