The year is young, but there's already a strong candidate for the coolest single of '04: Twista's ''Slow Jamz,'' a twitchy tribute to baby-making soul currently tearing up the Billboard singles charts. Riding a classic Luther Vandross sample, the speed-rapping Chicago MC and friends -- rapper-producer Kanye West and comedian-singer Jamie Foxx -- have created a meta-R&B hit: a slow jam about slow jams. In between name-checking classic bedroom crooners (Gladys Knight, Marvin Gaye) and some lesser-knowns (Ready for the World), Twista and pals spit out risque rhymes (''I'm play this Vandross, you gone take yo pants off'') about the seductive effects of a successful booty track. ''People have told me that they use [''Slow Jamz''] in the bedroom,'' says Twista. ''That's the kind of vibe I wanna create -- a rap track that will have your attention and make you wanna get down like that, get a bit freaky.'' Mission accomplished.