Hayden Panettiere (a.k.a. the new Julia Roberts) turned vicious with reporters on a red carpet in Hawaii over the weekend. Look out, folks. Now that she's no longer with Milo Ventimiglia, Hayden can let her witch flag fly and not pretend to be mature and sweet anymore. Not that we were fooled. Or maybe she was just having a very bad day. In Hawaii. On a free trip. According to Us Magazine, the 19-year-old "Heroes" hottie was "testy" when she walked the red carpet at a charity fundraiser benefiting the Rehabilitation Hospital of the Pacific Foundation on Sunday in Honolulu.