YOU DUN KNOW is basically a sayin used by pure badmen, rudeboiz, rudegaldem, and all the mandems locked on inside. it means YOU DUN KNOW you wud use this sayin in sad or scary times when mans got his back against the wall and the gunchester/bombingham mandems are comin at him with baaare machete bled ya get me? Its hard to explain so just read the examples bit yeah while i cut off my foreskin yeah U DUN KNOW its gunna hurt yeah
geekman/wasteman - "hold tite the beef n ting"
rudeboi/man with 4skin - "yeah blad you dun know da myspace dot com yeah forward slash beng beng yeah hold tite skepta jme you dun no blad"
geekman/wasteman - yeah man blat blat u dun know the facebook and the faceparty thing fam ya get me?"
rudeboi/man with 4skin - "oi shhut ya mouth waaasteman durkhead YOU DUN KNOW facebook is for fassys and man with no 4skin big up the gears of war mandem yeah one love one life lets get together and feel my right............... testicle ya dun no fam im lyrically sick yeah 1 love breh"