My understanding is that it’s a signal that you just took an insanely exclusive drug trip. The kind that would kill you if you didn’t space it out by a few years each time, but the high is unlike anything in this world - literally- and if you have to ask how much you can’t afford it - it’s more about connections than money. Somehow it blackens your eye. The extreme stories say something actually goes into your brain or soul through your eye. Only the elite even have access to it so they wear the black eye proudly