It turns out, there's not any kind of lock on it or anything. You can open it right up, if you are so inclined.
As with most bulletin boards, there are a number of extra pushpins / thumbtacks pushed into the cork, waiting to be used on the day when whoever it is that posts the notices somehow manages to post two dozen of them on a board that's maybe two feet wide. At the moment, there's only one piece of paper in there, so there are a bunch of extras. There are five silver thumbtacks (four big ones and one smaller one), and then a variety of colored plastic pushpins, mostly white and yellow, but with a few blue and red in there, too.
Anyway, riding in the elevator one day recently, I organized them by color, because I like symmetry.
And then a day or two later, I noticed: someone had moved them. They were rearranged a little from how I'd organized them. So I rearranged them a little more, changing them from a big triangle to a sort of fish shape.
And now it's become a game.
Any time I'm alone in the elevator, I quickly pop the door open and change things around. It's at most five floors (from my office on the 3rd floor to the parking lot entrance on 2B), so there's not much time. Maybe all you can do is disrupt the existing pattern, or swap some colors around. Make the circle a little more regular. Arrange the five yellows into a quincunx.
And then later, you see what else has changed.
I have no idea how many other people are playing, or if I'll ever know who they are. I don't think I want to know; it's this secret little unspoken conspiracy, and the mystery is part of the fun.
Today I added a pushpin.
A silver one.
That I took from one of the boards outside the cafeteria, specifically for that purpose.
This made me happy.