Green’s Dictionary of Slang

snap n.³

(US black) a wisecrack, a witty retort.

1994		Percelay et al. Snaps 3: African-American culture has often been referred to as an oral culture, one rich with storytelling and verbal repartee. Among the most interesting but least examined of these verbal traditions is ‘the dozens,’ a ritualized verbal contest in which the object is to hurl insults or ‘snaps’ against an opponent.
2003		J. Lethem Fortress of Solitude 46: ‘Your mother’s crazy,’ Henry said. He didn’t say it as a snap, like yo mama’s so ugly bigfoot takes her picture, but instead with admiration.
2006		J. Ridley What Fire Cannot Burn 34: He used to crack wise [...] Call it snaps, call it the dozens. Call it a sense of humor.
2017		comment at genius.com Loski – one of da oldest harlem members , he is out of jail now and his snap is loskiloose.

In derivatives

snapper (n.)

(UK black) a rap lyricist.

2007

D.S. Mitchell Killer Tune (2008) 41: He had to stand out from all the other snappers on the scene.