This is a shortened version of saying demonic. It is often used for describing something that is possessed, in most cases, a cat.
Girl - Dude! Are you cutting your self?

Guy - No! My cat was being all deamo last night! and attacked like no other

Girl - Ohhhhhhh

Guy - Yeah I know! He dun shredded me up like some cheddar cheese though
by Nich1111 February 2, 2011
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