It could be anything, like a pile of garbage with a coca-cola vending machine on top of it, or just a piece of equipment.
Or, like in a video posted in this thread, an unsuitable writing on the wall, there seem to be a lot of them: http://i.imgur.com/0QL7a.png (similar size btw)
Or, like in a video posted in this thread, an unsuitable writing on the wall, there seem to be a lot of them: http://i.imgur.com/0QL7a.png (similar size btw)