Green’s Dictionary of Slang

arm and hammer adj.

[Arm and Hammer, a US brand of baking soda]

(US) second-rate, unimportant.

[US]Simon & Burns ‘Cleaning Up’ Wire ser. 1 ep. 12 [TV script] Savino ain’t nothing but an arm and hammer charge.
Jeezy ‘In the Air’ [lyrics] Arm and hammer, here we go, here we go.