Somewhere, Elvis Presley is swiveling his hips, curling his lip and grumbling, "She can do better." The New York Post reports the King's bombshell 17-year-old granddaughter Riley Keough (mom is Lisa Marie Presley) is dating porcupine-coiffed popster Ryan Cabrera, 24, the former flame of Ashlee Simpson. And she's apparently smitten. According to the paper, the duo was celebrating Ryan's birthday last week at a New York hotspot when a flirty model nabbed the warbler's hat and took off. Keough, who's also a model, quickly gave chase, jumping on the sticky-fingered looker and seizing the headgear back.