As cold weather sets in, a little naughtiness raises the body's temperature. So sensation-savvy Club Onyx developed the perfect solution with Fetish Night every week. Saturday, November 16, brings a "Sexy '70s" theme, as the 13th Street club invites you to bring not just your best toys, but your neglected wigs, gold chains and even those funky old bell bottoms. Just the thing to spark anyone's libido, the club will have costume prizes along with the usual "interactive areas." DJs Rob and Fleisch will hold the master whips, spinning enough techno and industrial sounds to give you hot flashes. Like watching? Being watched? Looking for a place to fulfill your fantasies? Onyx invites late-night lascivity in an erotic environment that's safe as well as sexy. At Onyx's Web site, onyxdenver.com, you can learn what's encouraged and what's not. Break out your funkiest, foxiest attire and, this time, don't behave.