UDEK 

Short form for U Dont Even Know. Also pronounced U-DECK to troll people.

Guy #1: UDEK
Guy #2: Wtf man I Deck?
Guy #1: LOL UDEK SO HARD
Guy #2: WTF are u talkin about
Guy #1: UDEK about UDEK

UDEK by AnHeroBarrellRoll August 5, 2009

UDEKM 

You Don't Even Know Me

Usually used when someone is passing judgments about you when they have no idea who you are or anything about you for that matter.

but UDEKM

UDEKM by yyyyyyyyyyyyyy? July 6, 2010