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When someone wears a hat to rid themselves of bed head because they didn't have time to take a shower.
Person 1: Dude i was running so late today i only had time to take a hat shower. Can you tell?

Person 2: Well you kinda smell but you look oh so fine. No homo
by GrandRap Godfather July 15, 2008
Instead of a taking a shower or shampooing one's hair in the morning (generally due to tardiness), simply wearing a baseball cap over one's ratty hair.
Dude, I was late for class, so I had to take a hat shower.
by Tricky February 05, 2008