This is the URL at the bottom of the latest teaser posters, and it redirects to a Facebook page:
https://www.facebook.com/themeninblacksuitsarereal

At the time of writing it already had 3261 likes, so expect that to reach 6 figures in a few months.

I’ve uncovered that there’s these Men in Black suits who monitor and police alien activity on earth. Up until now no one believes me, so I’m on a mission to prove that they’re real and that’s why I started this Facebook page. More soon.

The above first post there is pretty weak, considering it is obviously created by the folk at Columbia Pictures or someone they hired… and not an individual.