asscrab
similar to the facehugger from Alien and the Headcrab from halflife, the asscrab kills you after it used your body, but the asscrab attacks your ass instead of the head
beware of the asscrab
asscrab
n.) Generally used for a person or thing who, apart from being a complete asshole, is also very obviously crabby.
God damn it, Andrew. You're a fucking asscrab.