About six months after the Air Force made its decision to go with the ugly child, an officer writing about it in a professional journal wondered what it might be named. He then recalled that Republic's F-84, which on hot days sometimes could not get airborne, was called the Groundhog, or just "Hog." When the swept-wing model of the F-84 appeared, also with ground-loving characterists, pilots called it the "Super Hog". Since the Republic F-105 was also a ground lover and called the "Ultra Hog" by pilots (later the F-105 became much better known as "The Thud") the writer wondered if the A-10, which promised to be the meanest and ungliest plane ever to join the Air Force, should perhaps be called the "Warthog."
The Air Force leadership chocked on that name and Fairchild dutifully came up with something much more distinguished. Wanting to capitalize on the immortal reputation of the rugged P-47 Thunderbolt that was so effective as an air-to-ground warrior in World War II, they decided to invite two WW II Thunderbolt pilots, both highscoring aces, to a ceremony and christen the plane the "Thunderbolt II".
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And the nickname the pilots finally decided to use for the airplane? It certainly isn't "Thunderbolt II", the nickname Fairchild convinced the Air Force to accept. The pilots almost gag when they hear someone using that name.
In principle they liked the nickname "Warthog" and they have semi-officially adopted it because it symbolizes what they perceive to be the airplane's two key characteristics; like the real warthog, it is both mean and ugly.
However, one never hears the pilots themselves using that nickname. "Warthog" is strictly for polite company (and for book titles). Within the community of pilots they shorten the name [...] because of its ugliness. The pilots call their airplane the "Hog", and, proudly, they call themselves "Hog drivers"