For his role as a West Coast gangbanger in Thicker Than Water, Bronx-based hip-hop figure Fat Joea last-minute replacement for Snoop Doggreportedly ad-libbed the phrase "It's all gravy" to give his character L.A. credibility. Though his subtle method touch will likely escape most in the theater, it's this commitment to authenticity that makes Thicker Than Water imperceptibly better than other cheap, incoherent rip-offs of GoodFellas and Scarface. There's a germ of a good idea in the story of rival inner-city gang leaders Mack 10 and Fat Joe, who set aside their arbitrary differences to produce music outside their double-crossing corporate label. Never mind that their money-raising scheme involves selling a massive amount of drugs to a goateed white slacker type; at least their collaboration is founded on a non-violent, entrepreneurial spirit. But it's not long before they get mixed up with Hollywood Hills drug-lord CJ Mac (who enters to Chilldrin Of Da Ghetto's "Druglord," a helpful musical cue) and the requisite bloodbath ensues. Designed more as a promotional tie-in to its two-CD soundtrack (both CJ Mac and Chilldrin record for Mack 10's vanity label) than as a piece of entertainment, Thicker Than Water throws in a couple of wholesome subplots, but mostly it's about guns, catfights, unmotivated freeze-frames, and crudely improvised dialogue miked from about a block away. Ice Cube and B-Real show up for an afternoon's worth of scowling and cue-card-reading, respectively, in celebrity cameos well suited to this numbingly obligatory venture.