The U.S. Naval Institute posted on X that, in earlier days, ship flagbags sometimes contained a pennant that would express frustration and/or confusion at other vessels. I traced the origin story down to Vice Admiral Milton E. Miles, who described the pennant in his book A Different Kind of War: The Little-Known Story of the Combined Guerrilla Forces Created in China by the U.S. Navy and the Chinese During World War II.
In 1934, Miles was captain of USS Wickes, a destroyer then responsible for being the rearmost ship while in a formation operating off the coast of China. He thus had the opportunity to witness blundering movements of other vessels and wished to communicate his distress. His wife suggested the above design which he then had made and later transferred with him.
Miles had amusing pre-war interactions with a Japanese admiral over the pennant which later led to questions directed to him in Washington, D.C. You can read his story here.
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