Demi Lovato is blowing up the internet with a bang…

During Jessie J’s performance at 99.7 NOW!’s 2014 Triple Ho Show in San Jose, California this week, she shocked the audience by bringing out the 22-year-old part-Mexican American singer to perform Ariana Grande’s vocals on the hit single “Bang Bang.”

Jessie J started out her performance at the SAP Center solo, but teamed up with Lovato for one epic duet that’s now gone viral.

When it came time for Garnde’s verse, Lovato stepped out onstage. Naturally the crowd went nuts! Dressed in a black crop top and skirt, the always spunky Lovato owned Grande’s portion of “Bang Bang,” with her voice sounding great as she belted out those high notes just like Grande.

After the surprise performance, Lovato tweeted, “That just happened….. Thank you SO much @JessieJ for having me on stage for Bang Bang… It was an honor!”

Jessie J also tweeted a sweet message to Demi: “WOW!!! @ddlovato is a dream to be on stage with!!! Thank you girl!!! You sang yo ass off!!! #bangbang…”

The video has already garnered 800,000-plus views on YouTube.