Them niggas be drumming
He’s saying “them niggas be drumming” as in shooting guns. Continuing on from the line before, “don’t be fuckin' with my youngin’s”
His homies, gang affiliates, be shooting Machine-Gun DRUMS!!!
Hence, the creation of the verb, DRUMMING!
To help improve the meaning of these lyrics, visit "3hunna" by Chief Keef Lyrics and leave a comment on the lyrics box