Halsey Performs 'Remembering Sunday' With All Time Low, Living Out a Teenage Dream: Watch

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Halsey performs at the Okeechobee Music and Arts Festival on March 2, 2018.

Halsey has made it known that she was (and still is) an emo kid, and she lived out an ultimate emo kid dream last night (Aug. 19). The "Bad at Love" singer joined All Time Low on stage at New York City's Pier 17, singing her favorite song "Remembering Sunday" with the pop-punk group.

All Time Low's Alex Gaskarth typically plays a stripped-down version of the band's singalong track "Therapy" about halfway through their set, but said they were going to do something a little different in NYC before beginning "Remembering Sunday." Even though it was a fitting switch for a Sunday night show, little did fans know it was because Halsey was backstage -- and they went as crazy as she probably was on the inside.

"I used to play 'Remembering Sunday' at every coffee house I played when I first started out. Tonight I played it with the boys in NYC and it was a dream awake," Halsey posted on Instagram along with pictures with All Time Low. She clearly couldn't get over what had just happened, as she also took to Twitter to express her excitement for the moment: "Can u believe I sang my favorite song with one of my favorite bands tonight ????"

The All Time Low guys were equally pumped to have Halsey join them, with Gaskarth commenting "Such a vibe. You are a legend. Always a pleasure" on Halsey's Instagram pics, and drummer Rian Dawson adding, "What an incredible moment. Fuck yessss" on his own post.

Watch Halsey sing "Remembering Sunday" with All Time Low and check out some pictures from the special moment below.