A round blue sign with a yellow dot on it, placed on a 1.7-meter-high post in the middle of the pig enclosure at a local petting zoo, seems at first glance like an absurd detail, a joke, or a forgotten object without a purpose. Yet, it's often precisely these kinds of trivial, inexplicable interventions in public space that can have a remarkable social impact—not through their direct function, but through the meanings visitors ascribe to them.