you must have a hairy ass for this to work. its when you take a huge extremely wet shit and you wipe your ass and shit gets stuck in your ass hair without you knowing and becomes crusty.
"man i found out i had ass crust yesterday when i was picking my crack."
by coorreey August 16, 2006
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A derogatory term used to describe anyone who pisses you off. Derived from the leftover pieces of shit left in your ass after the umpteenth swipe.

Not to be confused with asshat.
Student A: What'd you get on the science test?
Student B: 64. Mr. Bober's a dick.
Student A: Really? I thought it was easy; I got a 110!
Student B: *glares* You cocky ass crust. Piss off.
by Ninja47 June 11, 2010
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When you dont wipe

Or

Someone who joins your group chat uninvited
Ew this ass crust joined this chat
by Jagwla November 27, 2018
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