Green’s Dictionary of Slang

wigga n.

also whigger, white nigga, wigger
[SE white + nigga n., invariably derog. term used by blacks to sneer at those who ape their culture and by whites in a generally racist sense]
[1990s+]

1. (orig. US) a white person who adopts a black, spec. hip-hop/rap, lifestyle and is not merely a consumer of the records, but attempts to emulate what is otherwise an autonomous black culture.

2. (US campus) an African American who identifies with whites.

In compounds

wigga-speak (n.) (also wigger-speak)

the quasi-black patois adopted by such young men.