Looking for a witty, dead-on parody of the hard-core rap scene? If so, you'll probably watch CB4 ticking off the missed opportunities. This raucous comedy charts the rise of a furious trio of gangsta rappers, CB4 (it stands for Cell Block 4), who take their name from the prison wing in which they supposedly did time. The joke is that their outlaw image is all a fraud. Led by a sweet-faced kid named Albert Brown (Chris Rock), who starts calling himself M.C. Gusto, CB4 are just middle-class kids from Locash, Calif., (that's right, Locash are you laughing yet?), who put on prison work shirts and churlish scowls and con the public into thinking they're hard-shelled thugs.
Early on, we see the group trying out various stage personas at a local rap club a scene seemingly inspired by the one in This Is Spinal Tap that flashed back to the band's flower-power days. Except that here, the joke isn't given enough time to settle in. The CB4 crew appear for an instant in back-to-Africa dashikis, then with shower caps on their heads (are you laughing yet?), and then the routine's over. A little later, they're rapping in a car along with a Run-D.M.C. tape a scene obviously inspired by the ''Bohemian Rhapsody'' sing- along in Wayne's World. Except that here, nothing crazy-silly is going on; the tape player just starts playing at the wrong speed. Finally, we get the obligatory mock video clip: It's a rape-and-pillage fantasy called ''Straight Out of Locash,'' and it features the rappers strutting along Los Angeles back , alleys, sticking their ferocious mugs in the camera, dissing the cops... but wait a minute, it looks exactly like a real rap video.
It was at this point that I began to realize why nothing in this movie is very funny. CB4 would like to be a savage hip-hop lampoon, but, in fact, the film strikes a cautious balance between satire and homage. It can't decide whether it wants to ridicule CB4 or hold the group up as role models. What we're left with is a soggy catalog of rap cliches.
Chris Rock has done some amusing hip-hop parodies on Saturday Night Live, but in CB4 he makes an alarmingly ascetic rap hero. With his high, strangulated voice and pretty-boy-scarecrow physique, Rock lacks authority on the big screen, and so the movie has no center. We can certainly believe in Albert as a middle-class poseur. What CB4 never begins to satirize is the character he's posing as: the nihilistic rap hustler whose ''criminal'' image is inseparable from his desire to make a killing in the record industry. You get the feeling that gangsta rap's show-biz intimidation tactics did a job on the filmmakers, too. C-