“The North Koreans we’re (sic) preparing to shoot missiles in the airspace of an area that had been declared by both sides NEUTRAL. Nevin Cunningham and Gino Quist, US Air Force (USAF) SR-71 crew, wanted to give their own personal response.
Flying the SR-71 #967 on a two Loop sortie of the DMZ on Aug. 25, 1981 Nevin flicked on fuel dump switch during a final pass and in quick Morse code spelled out the four-letter expletive:
“F**k” off to the North Korean regime.
North Korean ground trackers who were ATTEMPTING to follow the SR-71 visually were watching. This message they were sending sure did provide lots of laughs back at the Habu’s bar at Kadena Air Base.”
Source: That time an SR-71 Blackbird crew used the Morse code to say “F**k” off to North Korean regime (They were preparing to shoot SAMs in neutral airspace) – The Aviation Geek Club