It's official: Now matter how you spin it, 'Bang Bang' is destined to be a star-studded hit. For example, during Jessie J's San Jose, Calif. concert on Wednesday night (Dec. 3), Demi Lovato made a surprise appearance to sing Ariana Grande's part of the song.

Luckily for those of us who couldn't see the performance in person, one fan taped the duet, which you can watch above. The crowd was clearly amped as Jessie began to belt the track. However, when Demi appeared, the audience went positively wild.

“She might’ve let you hold her hand in school, but I’ma show you how to graduate,” Demi sang over the roar of the crowd. (By the way, she even rocked an Ariana-esque black lacy crop top!)

Naturally, Demi slayed her portion of the song because Demi. Jessie J and Demi's vocals sound so, so good together, furthering our dreams that they need to do an official duet, like, ASAP.

Watch Jessie J and Demi's performance of 'Bang Bang' in the video above!

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