Demi Lovato Sang Ariana Grande's 'Bang Bang' Verse with Jessie J & Made a Crowd Go Crazy! (Video)

Demi Lovato and Jessie J perform together on stage at 99.7 NOW!’s 2014 Triple Ho Show on Wednesday (December 3) at the SAP Center in San Jose, Calif.

The ladies were both on the lineup at the concert, but Demi surprised the crowd during Jessie‘s set by joining her for “Bang Bang” and singing Ariana Grande‘s verse!

Of course, the crowd went absolutely wild and it’s almost hard to hear her sing in the video captured at the concert.

“😱😱😱… That just happened….. Thank you SO much @JessieJ for having me on stage for Bang Bang… It was an honor!” Demi tweeted.