Abbreviation for "First In, First Out", and abstractly means that the first item placed into a container or list will be the first to be removed. The system is used by fine resturaunts like McDonalds in order to assure freshest average food quality, though it doesn't address the omnipresent "half of the stock is expired" or "the refrigeration temperature is too high" issues. It is noteworthy that many employees ignore the system altogether in favor of grabbing the most convenient box.
FIFO! FIFO! FIFO, FIFO, its off to work we go. *whistling* FIFO, FIFO, FIFO.