Good Girls Gone Bad

Miley Cyrus isn't the first pop star to show her naughty side – check out how Britney, Christina, Rihanna and more stars went from PG to R-rated

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JESSICA SIMPSON

After always coming in third behind fellow blonde popsters Britney Spears and Christina Aguilera, the vocal virgin showed that you didn't have to have sex to be sexy, writhing with the best of them in the humptastic 2001 video "Irresistible."