Rap can be as nasty as it wants to be, and, thanks to the 2 Live Crew obscenity trial, everybody knows it. Yet explicit rap tunes everything from the exaggerated sexual boasts of the Crew to the ''gangsta'' playacting of N.W.A. pose a new and complex set of questions. Are sexual rap songs merely dumb-fun party records Redd Foxx set to a drum track or should they be treated as appalling antiwomen tracts? Are rappers who talk like thugs trying to dramatize conditions in the black community or merely toughening their image? Do they actually encourage violence? None of these new records fully answers those questions, but in its own way each addresses the contradictions inherent in explicit rap.
Just in time for Christmas, Ice Cube crown prince of the gangsta-rap crowd, thanks to the platinum success of his debut album, AmeriKKKa's Most Wanted, released last year has unleashed Kill at Will. This seven-track EP recycles two tracks from AmeriKKKa, adds three pieces of blatant filler (including ''I Gotta Say What Up!!!'' on which he thanks other rappers for support), and features only two new songs, though each almost makes you forgive the rehashes elsewhere on the record. One new song is ''The Product,'' a hard-slamming autobiography; the other, ''Dead Homiez,'' is Ice Cube's brooding public-service message, somberly dramatizing ghetto violence with funky music in the style of a '70s blaxploitation film. C+