Nose-art began during World War I when squadrons would gild their flying machines to distinguish friendly aircraft in the confusing frenzy of dog-fights. In time, individual pilots had additional art work applied.
During World War II, crew-chiefs became protective of their planes and pilots. This camaraderie often extended to arranging the best nose-art available. Nose-art often reflected extremes: bravado or posturing and yet, sometimes sarcasm about war.
A pilot and the crewchief of the 357th Fighter Group admiring risqué nose art. Note the ten aerial victories beneath the canopy.
Surviving sample of B-29 bomber nose-art.
Humor was another favorite theme
Photo by author @ Wright-Patt AFB display