Green’s Dictionary of Slang

snowflake n.2

[snow n.1 (1e) + SE flake/flake n.2 (1)]

(US black) a white; or a black person who apes whites; also attrib.

[US]B. Rodgers Queens’ Vernacular 63: black man [...] snowflake.
[US]L. Heinemann Close Quarters (1987) 225: One a us brothas gotta be the Crazy Nigga roun’ here since Snowflake Surtees — that chicken-shit fucken shine — took off.
[UK]R. Hewitt White Talk Black Talk 237: It’s just a good laugh, like I go, ‘alright, rassman?’ an’ he’ll go ‘alright, snowflake?’.
[US]‘Master Pimp’ Pimp’s Rap 108: Sampson, the bondsman, could give me the rundown on this snowflake whore.