Shoe Event Horizon

(From HitchhikersGuideToTheGalaxy)

A hypothetical type of economic collapse caused by a catastrophic decline in the quality of an economically critical product (e.g., shoes), requiring more and more of the economy being focused on making more shoes, whose quality continues to drop as they are made by less and less skilled workers, resulting in a downward spiral. Eventually, the entire population becomes employed in the production of unwearable shoes, causing famine and the collapse of the civilization.

As with the GreyGoo catastrophe scenarios, it is probable that various factors that would halt such a cycle long before it reached the critical point in the real world.