Many years ago I was OIC liquid refreshment for a NATO Tiger Meet, a role I was "draughted in" for at short notice due to the original incumbent being posted.
Our squadron had previously made contact with some local breweries and I was able to get a really good deal from a major supplier, dealing direct. The NAAFI manager heard about this at a late stage and demanded that all beer was to be supplied through his empire. From what I remember, this involved a hefty surcharge on the price I had negotiated direct with the brewery.