Britney Spears Says 'Till The World Ends' Has 'Good Energy'

Britney Spears got her fans amped up for her forthcoming album, Femme Fatale, when she released its second single, "Till the World Ends," on Thursday. The chugging, Ke$ha-penned club banger is all about getting your dance on. And when Spears stopped by Ryan Seacrest's radio show on Friday (March 4), she admitted that the song just felt right for her as soon as she heard it. " 'Till the World