'When a new pilot arrived at Takhli or Korat, he immediately purchased a 'go to hell hat' (an) Australian bush hat at the Post Exchange. For each mission flown against North
Vietnam, he etched a black hash
mark on the front of the hat; for missions into the Hanoi area (Route Package 6), he penned a red
mark on the hat. Status in an F-105 Squadron often boiled down to how many red and black
hash marks a pilot wore, with the ultimate status symbol being the 100-missions patch he recieved at the end of a tour.' *excerpt from; "Fast Movers: Jet Pilots and the Vietnam Experience" By John Sherwood