It is a joke or a riddle, depending on your point of view. I used to be a high school math/science teacher, so this fits in at the intersection of those. If we have national standards for physical things like length, or mass, why not a national standard for a mathematical constant? It's just a ring with a scale on it that measures the circumference. Every now and then, a technician checks the value and records what they see in the log.

Even my fellow teachers struggled to grasp the humor of the thing. I suppose I'm a little strange.