When the hair around your ears is pressed against your head due to extended amount of time wearing a headset. More specifically, while playing halo.
"After we played Xbox Live for 2 hours I had to go to work. My manager yelled at me for having halo hair!"

See headset hair for more generalized use.
by SiAo April 30, 2009
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When a person has a bald spot on the back of their head and is surrounded by hair, which makes the back of their head appear as though they have a halo of hair
"Wow dude, look at the professor! He has a hair halo."
by lifeguardstatus November 10, 2016
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