https://www.pcgamer.com/grand-theft-auto-6s-announcement-is-a-good-hoax-but-still-a-hoax/

I’ll eat my underpants if it’s real, but an in-game message in GTA Online has been teasing the arrival of Grand Theft Auto 6, absent any other fanfare. The message purports to come from Rockstar and it’s been reported by multiple people on different platforms, accompanied by screenshots. It’s complete nonsense, but convincing nonsense. 

The message, simply stating that GTA 6 is due out next year, has been popping up over the weekend, and while it's almost certainly completely fake, it does look official. It’s not, of course, but you can see how it could send fans into a frothing frenzy of speculation and hopes.