This better be a stupid viral marketing scheme or trolls from SA or something.
I saw this earlier as someone is spamming 4chan with threads about it. I doubt that this will get any rape-burn-pillage mobs out and the worst case scenario is someone getting paranoid over this and shooting at people they think are a threat.
Oh, don't you worry. It is a hoax.
I feel like the only who has bothered to even attempt to debunk this with proof and confirmation.
You debunked the wrong thing, though. Your link is about a fake news story where supposedly a Purge event happened in Chicago and 112 people died. This thread is about people threatening to hold a Purge in Louisville.
Also a hoax, in the sense nobody followed through*, but of an entirely different sort.
*Or at least, not enough people to matter.
