''Got a chip on my shoulder and a MetroCard,'' spits ex -- Masterminds MC Kimani Rogers on this hip-hop salvo, and he ain't kiddin'. Named for the first black Muppet on ''Sesame Street,'' the duo (with DJ Mr. Len, of legends Company Flow) open their brilliant mess of a debut with a long skit-song about bogus underground rappers. Skip it and begin with ''Lately,'' a terse banger in which you meet an edgy guy two years sober with ''emotional baggage'' from his dad, ''bills out the ass,'' and ''voices in my head that just won't subside.'' Then call Ja Rule and ask him to explain ''realness'' to us again. The pair also have hooks and a warped sense of humor, and by the time Rogers is living large over a Yeah Yeah Yeahs sample (on ''I'm So Rich'') or shouting about Kurt Loder jacking him at the ATM, you're happy to indulge his bleaker moments. SISTER-IN-ARMS Jean Grae drops in for some cold-sweaty verses on ''Insomnia 411''; her latest, ''The Bootleg of the Bootleg'' EP, is another hopeful sign that rap isn't brain-dead.