Literally, "You don't know", but meant ironically because your homie does know.
"y0 Tone, u get mad high at the party, fam??" - "DUNNOE"!
In the art of DJing, the practice of placing one or more CDJs between a vinyl turntable and the mixer, hence pushing the decks inconveniently farther apart.
I busted out double-copies of Boogie Down "The Bridge is Over" at the party but they were Discmanspreading and it was messing with my routine