The Black Eyed Peas with Justin Timberlake and Christina Aguilera

Old school, new school, too wack for school -- the Black Eyed Peas have outlasted most of the other anti-gangstas of the '90s, partly because they're smart enough to never stop getting stupid. Two tracks into Elephunk, their newest and (finally) masterful platter, will.i.am, apl.de.ap, Taboo and new addition Fergie enjoin the house to "get retarded in here" -- and they're not kidding. The BEP know that hip-hop, at its most elemental, sweaty and joyful, must cast off all pretension and inhibition if the groove is really going to groove. "I'm a freak and you know it," apl confesses over a scratchy Latin grind. "You're a freak and I know it." In a phrase, that's the mind-blinging knowledge of the Black Eyed Peas.

Although they build a pulsing pastiche out of frizzy funk, swinger lounge, Hitsville sunshine, Jamaican house, psychedelic rock, chunky breakbeats and a whole lot of Latin riffs (is that a reverse looped Santana solo on "Sexy," and are those horn blasts on "Hands Up" copped from I Love Lucy?), the Peas remember the physics lessons of their SoCal breakdancing schooling: Keep the beats supple and solid, keep the flow keyed to the body -- and the mind will follow. They even take cameos by Papa Roach and Justin Timberlake and make them sound, well, heavy. And though Elephunk primarily preaches a get-down gospel, it doesn't waste time on logo-rapping or stilted soap-boxing. The conscious vision of "The Apl Song" -- a hymn to the nightmares and dreams of ghetto-life -- and the single "Where Is the Love" -- a sweeping, symphonic meditation on peace -- remind us that, transformed by the Black Eyed Peas' imagination, boogie and beatitude just might be a single truth.

(The Black Eyed Peas also perform for free at 1 p.m. on Saturday at the U. City Vintage Vinyl.)