Green’s Dictionary of Slang

dun n.

also dunn
[var./pron. SE son]

(US black) a friend.

X Clan ‘Xodus’ 🎵 Here comes the rhythm of the warriors, dun.
[US]Nas ‘Genesis’ 🎵 Stop pointing that at me, dunn, take the clip out.
Big Noyd ‘No Where Else To Hide’ 🎵 Look, dunn, I’m not dumb, I roll with a big gun.