crust Share definition Flag used to desrcibe an object or person with either indescribably dirty, sketchy, horrid, pputrid, unfathombale, flaky, or fugly characteristics. Yo that guy is so crust, he smells like shit and its all oily crust by lizzybmomofenz December 14, 2010 0 0 Get merch Get the crust mug. Buy Now — $32.95 See more merch