Anyone who's seen the 2 Live Crew in action or watched their pathetic performance on last year's MTV awards already knows that Luther Campbell and gang are one of the most inept live acts in history. But even that low standard won't prepare you for Live in Concert, recorded last year in Phoenix. For your hard-earned dollars, you get a smidgen of music, namely lazy run- throughs of ''Me So Horny,'' ''The F---k Shop,'' and their other bawdy romps. But you get so much more: (1) Campbell leading the crowd in football-style cheers, including such rib-ticklers as ''Hey, d---suckers'' and ''Take your grubby ass home, bitch!''; (2) Campbell and the band indulging in repeated cheers of ''hey ho,'' as tired a rap-concert cliché as dry-ice fog at an arena rock show; (3) Campbell's insightful views on Southwestern culture, like, ''Guess you all f--- in the desert, huh?'' and ''Is Phoenix horny or what?''; and (4) muddy sound and ultra-cheesy packaging that must have set Campbell's record company back about, oh, $17. Perhaps the Arizona audience, which does a letter-perfect impersonation of a leering mob, should receive all the royalties: On Live in Concert, they work harder than the 2 Live Crew.