Fans at Demi Lovato's Concert at the Staples Center in L.A. received quite the surprise while the songstress performed her Camp Rock song "This is me."

The crowd burst into frenzy when, on Saturday, Sept. 27, Ex-boyfriend Joe Jonas joined Demi on stage to sing the song that featured them both back in 2008.

Many Lovatics (what Demi calls her fans) have been devoted fans since her Disney Channel movie "Camp Rock" in 2008. This is also where she and former Jonas Brother member Joe Jonas met. Midway through performing "This is me" Jonas popped up on stage to sing his part in the duet. The ex-couple, who only dated for a few months but whose relationship became a great deal in the Disney world, have remained good friends through the years.

The world is no stranger to Demi's addictive struggles as a teenager and neither is Jonas. Last year he even admitted through an open letter to having tried marijuana with Demi and Disney channel co-star Miley Cyrus for the first time. To everyone's surprise, Lovato said she was proud of Jonas, telling Us Weekly:

"I want to commend him for how brave he was," she said. "He never was able to share his side of the story. He kept it really quiet. I was going through my stuff, and he got blamed for a lot of it. We argue like brother and sister now. It's like, 'Dude, what were you thinking?' But it's all good. I was like, 'don't be embarrassed or whatever. I still love you. We're still family. It's all good.'"

Lovato and Jonas ended the song holding hands and with an embracing hug, proving to the crowd that they will support each other through thick and thin. At the end of the night, Lovato shared a photo of the two of them on her Instagram with the caption: "Thanks @joejonas for the awesome surprise!! #staplescenter #4yrssincewesangtogether #demiworldtour." Jonas also posted both a video and photo of the performance captioning it: "Surprise LA! @ddlovato thank you for having me, tonight was amazing. Fun keeping this a secret."

Watch the performance below.