Green’s Dictionary of Slang

sho’ ’nuff v.

[sho’ ’nuff adj.]

(US black) to be in earnest, to do something seriously.

[US]H.E. Roberts Third Ear n.p.: sho’ ’nuff v. 1. to engage in serious business; to be in dead earnest; e.g. We sho’ ’nuffin(g) today! 2. to agree with and to encourage someone.