Madonna's upscale ''Bad Girl'' empties a purseful of panties into a basin after a seamy night out. A leggy type in Naughty By Nature's ''Hip Hop Hooray'' gets her knickers in such a knot over watching Treach and Co. on TV that she must rush to wring out her own sinkload of delicates. And in Neneh Cherry's raucous new clip ''Buddy X,'' she wriggles, Houdini-style, out of her briefs before throwing them in the face of a leering homeboy. Bizarre coincidence or some sort of chick empowerment? Either way, Marky Mark's suddenly looking mighty tame.