Green’s Dictionary of Slang

charm v.

(US black) to ‘chat up’.

[US]Wentworth & Flexner DAS.
[US](con. 1982–6) T. Williams Cocaine Kids (1990) 90: All the Kids would rap, charm (talk to), or game to impress girlfriends; hang it up (insult) or fresh (compliment) male friends by using special words.