Another big moment was when Panic! At the Disco main man Brendon Urie joined Halsey on stage; you could practically hear the shrieks on Twitter. Just two days later, Urie spoke to Radio.com about the guest appearance, which marked the first time he was ever at Coachella, either as a performer or as a fan.

"We had tweeted at each other before," he says of his friendship with Halsey. "Because I was a fan of hers, and I covered one of her songs while I was live streaming; she heard about it and told me that she was a Panic fan. We had this mutual love and respect. So she asked me to perform, and of course I said 'Yes.' I was like, 'I'm gonna be out on tour, but I would totally fly in for this!'"

He said he left the song selection up to her; she wanted to sing "I Write Sins Not Tragedies": "She suggested that I come in during her song 'New Americana,' and she said, 'I really want to do "Sins,"' and I said, 'Yes! I would love to do "Sins" with you!'"