On last year's enigmatic but underselling "She Wolf," Shakira created some of the most eccentric dance- and hip-hop-influenced pop of the moment, and with her World Cup song "Waka Waka (This Time for Africa)," the Colombian star tapped the sound of an entirely new continent with help from Cape Town, South Africa's Freshlyground. Shakira places more emphasis on tropical music with her new single, "Loca," which opens with a throbbing, slow-burn merengue beat over which she seductively whispers a stark ultimatum: "Dance or die." The strengths of her most recent work aren't discarded completely, though. Shakira taps U.K. rapper Dizzee Rascal for a verse brimming with playboy boasts and cheeky Spanglish. While the duet isn't necessarily a home run-Dizzee and merengue make quite the jarring combination-it's just the latest evidence of Shakira's ability to make unexpected choices that widen her base and require repeat listening, without which one might not unpack her music's many pleasures.