The story
From hook + maneuver. From the anglicized onomatopoeia of the sound produced when practising the maneuver, with the inhalation "HOO" and exhalation "KEH" sounds.
Etymology from Wiktionary, CC BY-SA 4.0.
hook maneuver
Today it means: An anti-G technique to increase G-tolerance and reduce G-LOC incidences, which involves powerful inhalation, and rapid exhalation, resulting in breathing noises that sound like "HOO" for inhalation, and "KEH" for exhalation, (HOO-KEH... hook) Full definition →