Green’s Dictionary of Slang

1. (US) a young black man, esp. one who deals drugs on the street; thus fem. yoette.

1991		D. Simon Homicide (1993) 324: Clayvon Jones is simply a dead yo. [Ibid.] 350: Some sweet-voiced yoette wailing out the [...] lyric.
1997		Simon & Burns Corner (1998) 478: Paler-skinned hillbillies and hard-faced yos, toothless white trash and gold-front gangsters.
2002		Simon & Burns ‘Old Cases’ Wire ser. 1 ep. 4 [TV script] Fuckin’ yo did you a favour.
2006		G. Pelecanos Night Gardener 101: Maybe [...] the victim had been hitting some other yo’s girlfriend.

2. attr. use of sense 1.

2004

Simon & Pelecanos ‘Amsterdam’ Wire ser. 3 ep. 4 [TV script] (of a mobile telephone) The latest in yo-tech.