Last night, the song says, a DJ saved my life. Tonight it might be yours. And your lifeguard might be Russell Yarbrough, a.k.a. DJ Russell, whose CD deck breaks hearts, shakes hips and moves bodies at clubs all over Nashville, from the Connection to Club eXceSs. As the beatmaster who presides every Wednesday over Tribe Nashville's "Hump Night"-a double entendre he turns into a single with his sinuous, inhibition-lowering BPMs-DJ Russell indulges a flair for theatrics and a delight in melodic euphoria he's nursed since his high-school years in Murfreesboro. Inside the booth, he's equal parts king and Prince. Outside it, he's mentored many a local DJ. He's also a supersonic wit whose breathless riffing leaves friends laughing helplessly. No wonder the man in the booth gets so many upward glances all night long. When DJ Russell's spinning, Nashville is Emerald City. Pay attention to the man behind the curtain.