Britney Spears is not a girl, not yet a woman — but she's definitely off her rocker. Less than 12 hours after marrying childhood pal Jason Allen Alexander in Las Vegas, the 22-year-old pop tart arranged Saturday to annul the whole thing. In court papers posted at TheSmokingGun.com, Spears said her marriage should be dissolved because she "lacked understanding of her actions." Her record label was more blunt, saying in a statement that the pair "took a joke too far." For the record, the bride wore torn jeans and a baseball cap — neither of which I assume were white.