Noun
helmet hair (plural helmet hairs)
(idiomatic) An accidental messy hairdo resulting from the wearing of a helmet.
I look my best when I take my helmet off after a long motorcycle ride. I have a glow and a bit of helmet hair. Eric Bana
Hades took off his helm. His complexion was even paler than usual. He had a bad case of helmet hair. He was sweating and nervous and blinking like he had something in his eyes. "I am Hades," he said in a squeaky voice. "I love you. Rick Riordan