Demi Lovato joined Jessie J on stage for a surprise performance of 'Bang Bang'
This image appears in the gallery:
17 Celebs Who Dominated The Newspaper Headlines In December
5. Demi Lovato joined Jessie J on stage for a surprise performance of 'Bang Bang'
It was one of the BIGGEST tunes of the year for Jessie J, Ariana Grande and Nicki Minaj, so when Jessie had to perform 'Bang Bang' on her own, she brought out a special guest. Demi Lovato thrilled the crowds in the USA with her surprise appearance - and WHAT a performance it was!