UPDATE: Another poster (that is very similar as the first one spotted) has been found in the other house on Nuk3town, but it has something extra in the bottom right corner:
New teasers has been added into the outside of one of the house, and in the Courtyard on Nuk3town. The poster in the Courtyard also has an audio file that will start playing at some point during the game.
In addition, the Courtyard poster has an audio file linked which will randomly start playing.
— Ryan B. (@PrestigeIsKey) April 30, 2016