The article discusses the concept of Kanban, a visual signal that communicates needs or availability, and how it was applied in a simple yet effective way by an office manager to manage milk supplies. The manager used an index card on the last milk carton to signal when it was time to restock. This system is seen as a perfect example of Kanban in its original meaning, decoupled from the standard Kanban board design. The article highlights the importance of simplicity and self-explanatory systems in process design.