look up any word, like wcw:
 
2.
when sleeping next to a guy and he is so hairy that you think he's wearing a shirt, but its really just his chest hair that you're feeling.
"After seeing his hairshirt I was totally turned off"
"I bet his hairshirt comes in handy during the winter months"
by Lovehairshirts June 11, 2012
 
1.
a garment to induce some degree of discomfort or pain as a sign of repentance and atonement
My brother sinner, even though I completely understand your need for purgation, there isn't a man among us with half a conscience who doesn't keep a hair shirt as a permanent part of his wardrobe.
by dstrube December 17, 2010
 
3.
When a hairy guy shaves his upper arms right below the cuff of a short-sleaved shirt. When the shirt is removed, his hair resembles a hair shirt.
'You're swimming with your shirt on?'

'That's my hair shirt asshole!'
by Van Def May 16, 2005