R. Kelly's fondness for fornication isn't exactly a state secret. Yet there are moments of such supersonically unhinged sexual mania on Double Up his ninth and horniest album that you can only conclude that the guy who brought you the nutso R&B opera ''Trapped in the Closet'' has completely lost whatever was left of his dirty mind. Even Kelly's most earnest fans may not be sure whether to swoon, laugh, or cringe at the monkey and elephant noises in ''The Zoo,'' which lead to this pillow talk: ''I got you so wet, it's like a rainforest/Like Jurassic Park, except I'm your sexosaurus, babe.'' Then there's the Prince-esque ''Sex Planet,'' teeming with space-age metaphors that go exactly where any junior-high boy would hope: ''My rocket is so full of fuel, baby.... Girl, I promise this will be painless/We're gonna make a trip to planet Uranus.'' (Can an unfortunate reference to a ''black hole'' be next? Yes, it can.)
Those are just the sensitive slow jams, for the ladies. Much more of the new CD finds Kelly eschewing straight-up R&B balladry in favor of recasting himself as a hard-boiled hip-hop playa who's hitting the gentlemen's clubs with guest rappers such as Ludacris, Chamillionaire, and Nelly. Occasionally this results in a genuinely sexy nugget like ''I'm a Flirt,'' where he hooks up with T.I. and T-Pain over an infectious groove of percussive piano that's ''Bennie and the Jets'' gone urban. But more typical is the mundane way he and Snoop Dogg trade lewd banalities in the tired title track. ''Man, three's company/B----, call me Jack Trippa,'' Kelly croons, while Snoop barks out, ''Kiss me, kiss her, now kiss each other,'' seemingly narrating a children's primer on three-ways. As recently as 2004's relatively PG Happy People/U Saved Me, Kelly was still getting his Marvin Gaye on; now it's as if he's claimed 2 Live Crew as his true soul godfathers.
But Kelly is kidding, right? If you've ever watched him lip-synch ''Closet'' in its entirety with a straight face, you know this is a riddle for the ages. Is a sex-as-food anthem like ''Sweet Tooth'' (''You're lookin' like a big ole piece of cake'') deliberately campy? Your guess is as good as ours. And best of luck solving the larger puzzle of whether it's denial or defiance that has him ratcheting up the kinkiness even as his sex-crimes charges move closer to trial. But when he segues from ''Sex Planet'' into ''Rise Up,'' his treacly tribute to the Virginia Tech victims, it's perverse in a way he couldn't have intended. Just as surely as Justin brought sexy back, Kelly is bringing slightly creepy back. C