He was dubbed "Forty Second Boyd" for his standing bet as an instructor pilot that beginning from a position of disadvantage, he could defeat any opposing pilot in air combat maneuvering in less than 40 seconds. According to his biographer, Robert Coram, Boyd was also known at different points of his career as "The Mad Major" for the intensity of his passions, as "Genghis John" for his confrontational style of interpersonal discussion, and as the "Ghetto Colonel" for his spartan lifestyle.