Lounge acts are funny. They are. Maybe it's the sound of a semi-anonymous crooner switching identities from number to number -- usually only accompanied by the piano, that most dramatic of common household instruments -- that has inspired not one, but two Saturday Night Live parodies over the years (remember the Sweeney Sisters?). Maybe it's the idea of live background music. Maybe it's the booze. Regardless, it's a rare lounge singer who attracts not just praise, but a fan base. And Dave Hosley is that singer. Once you get over the goofy main construct, Diamond Dave's arsenal is sheer fun, and the dance floor at Petar's is packed proof of it. But it's not good clean fun -- just wait till Dave busts out his Nelly, R. Kelly, or Big & Rich, and the Saint Mary's coeds get their version of saucy. His repertoire spans Cole Porter to Bob Marley, the Killers to the Righteous Brothers, Johnny Cash to Kanye West. And with his Roland keyboard, Dell laptop, and headset mic, Dave smooths it all out just enough to get every patron in the house shaking something, at least.