It wasn't a joke. During the initial invasion of Afghanistan, one of the first pieces of infrastructure was a self-contained Burger King truck. Airdropped in on a C-130.

Even way back, one of the biggest things during the Pacific Theater in WWII was the fact that the US had three ships dedicated just to transporting frozen and refrigerated foods, so that the troops had fresh food. The ships colloquially became known as ice cream barges because they had the capability to make a ton of ice cream. The Americans in the Pacific were eating fresh meat and ice cream, while the Japanese soldiers were eating shitty rations. It was a major morale killer for the Imperial Japanese.