SAMFOX

SAMFOX represents an acronym (emphasis added):

"The base is also tasked, under what is known as "SAM FOX", to provide worldwide airlift for the vice president, the president's Cabinet, members of Congress, military leaders and other high ranking dignitaries. At one time, "SAM FOX", was used as a prefix to an aircraft tail number, during radio transmissions to identify Air Force aircraft that were transporting high-ranking VIPs, typically on foreign flights. The call sign prefix was constructed from the acronym SAM (Special Air Mission) and the initial F (Foreign), which at the time was represented by the phonetic word "Fox.""

Today, it represents "...a term that represents the ultimate in professional dedication."
(via, via)