Tune into 90.9 FM on a Friday night, and you'll probably wonder if the Federal Communications Commission has suspended its rules regarding off-color language. The truth is, the FCC would love to find the secret location of surreptitious, scandalous Nine-Oh-Nine and shut it down but quick. Until it does so, however, this is the place to listen to the thuggiest, nastiest, bootius maximus hip-hop you've never heard. DJs regularly interrupt the music for impromptu sing-alongs and shout-outs to homeys. And they take calls from enthusiastic partyers in Lauderhill, Sunrise, Hollywood, Plantation, and points beyond who are only too happy for the chance to talk on the air. However, 90.9 isn't legal, and sometimes you'll tune in to find nothing but dead air. As one late-night DJ recently explained, "When we say we underground, we mean underground."