Avril Lavigne was (and still is) the queen of 2000s Canadian pop music. While she's come a long way from the days of "Complicated," Lavigne is still rocking hard and giving great performances for her fans. Sometimes, she even stars as the special guest on stage. On October 25, Avril Lavigne joined Halsey onstage to sing Lavigne's hit "Girlfriend."

The incredible performance took place at Halsey's Halloween party, which had guests dressing up as rock stars from the 60s, 70s, 80s, and 90s. The hostess took the stage in a Marilyn Manson costume, while Lavigne was rocking a vintage Madonna look. 

Halsey's party wasn't just for the rich and famous. Fans were allowed to attend the party for free. However, admission did come with the condition of a mandatory donation to Los Angeles-based charity My Friend's Place, which provides assistance to homeless youth.

Avril Lavigne has still been going strong with her music career, despite struggling with Lyme disease and going through a divorce from Chad Kroeger of Nickelback. A conspiracy theory was also floating around that the real Avril had died and been replaced by an impersonator.

Halsey herself also went through a break up early in 2019 when she split from G-Eazy. However, rather than working through her breakup on social media, she instead chose to channel her feelings through her music. 

At the Halloween party, Halsey had been performing a set for guests at the party and brought Lavigne out as a surprise, and the audience seemed to love it, especially considering how many excited tweets there were about the duet.

"I can’t believe I got to witness Halsey and Avril Lavigne singing “Girlfriend” in the year 2019 !!!! ICONIC," wrote @iwanturmidnight.

"THIS IS THE MOST ICONIC THING IVE EVER SEEN," wrote @iammadz93.

Whether people made it to the party or not, at least they got to witness the iconic pop performance through some clips on Twitter, even if it's not really the same as being there.

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