Singer Demi Lovato met with female students in New York on Thursday morning (20Sep12) as part of her work as the new ambassador of an anti-bullying campaign.

The Give Your Heart a Break hitmaker was targeted by nasty schoolmates before she was famous, and the critics who took aim at the former child star's curvy figure following her 2010 and 2011 rehab stint, reminded her there are always people out there keen to drag you down.

So the new X Factor judge has stepped up to put a stop to the cruel behaviour of teens by agreeing to front the new Mean Stinks programme.

She tells People.com, "I had a really tough time when I was in middle school. People would write hate petitions (about me) and send them around to be signed. They'd have CD-bashing parties of my demos. They'd come to my house, stand across the street and yell things. It was a very emotional time for me."

On Thursday, the 20 year old visited fans at the Young Women's Leadership School to kickstart her new anti-bullying project, urging girls to wear blue nail polish on their pinky fingers to symbolise their pledge to have a Drama Free School Year.

She adds, "It's a conversation starter: 'Hey, why is your pinky blue?' 'This is a pinky promise that I'm not going to bully people.'"