What’s been happening
Working in an office with a large number of people can have its ups and downs. For example, the bathroom can usually be a disgusting place that not a lot of people bother respecting or cleaning when they use it. They just think the janitor will do everything so who cares in the end right?
Well, they would be wrong, because there are some messes that even the most desperate janitor won’t clean up. They just thought to put up a sign like this to shame whoever the person is making this gross mess. They don’t know who it is yet, but they are making it aware that they are being watched.