I'm so def, I ain't ever heard nothin'
Ab-Soul is extremely def, (as we can hear from his rhymes). He makes a double entendre with deaf, i.e. lacking hearing. He might refer to one of the most legendary labels, Def Jam, to show just how good he really is at rapping.
To help improve the meaning of these lyrics, visit "Smoke Again" by Chance The Rapper (Ft. Ab-Soul) Lyrics and leave a comment on the lyrics box