Green’s Dictionary of Slang

1. a form of address to a male [bo n.¹ (1) + jack n.¹ (4)/dick n.¹ (1)].

1970		in DARE.
1994		G. Smitherman Black Talk 64–5: bo-dick see bo-jack [...] ‘Bo-jack, my man, whassup?’.

2. the scrotum, the penis [bo n.¹ (1) + jack n.³ (1)/dick n.¹ (5)].

1994

G. Smitherman Black Talk 69: bozack Penis. Also bo-jack (older term).