I dunno at what school this photo was taken, but in my day, it was not uncommon for students in dorms to have mini whiteboards on their doors so people could leave messages (often in the form of specific private body parts). Mind you, I went to school before everybody had iPhones.

What I believe we’re looking at here is a photo of somebody’s (presumably Joseph Silva’s) door with a mini whiteboard and someone’s (again presumably Joseph Silva’s) contact info, which happens to be a Lemmy user.

The key word here is Lemmy, which would explain why OP shared this photo on !fediverse@lemmy.world.