If you attend one of Taylor Swift's concerts, you probably know there's a high chance she'll trot out at least one celebrity: It might be an old pal like Nick Jonas reporting for duet-duty, the entire U.S. Women's Soccer Team with Heidi Klum and The Weeknd, or several of her "Bad Blood" video stars staging a re-enactment. Last night's 1989 World Tour stop in Washington, D.C. was no exception — and the special guest was one of Tay's core squad members, Lorde.

Taylor posted a photo of the two sharing a squeeze onstage, with the caption, "When your friend flies across the world to surprise your crowd with 'Royals' because she's a wondrous angel." Lorde shared the same image, gushing, "looking over at my girl like "can u believe this is the kind of fun stuff we get to do for a living" THANKS TAY AND D.C. GETTING TO SING FOR U TONIGHT RULED."

Taylor teased her friend's appearance before her big entrance, telling them, "We talked about, earlier, the potential, if you kept up your awesomeness, for a potential surprise, didn't we?" It's hilarious to imagine an alternate scenario in which the "Blank Space" singer deems the crowd not-quite-awesome-enough and keeps Lorde to herself backstage.

Fortunately for all involved, that didn't happen, and after a bit more buildup Lorde took the stage. Soothe your FOMO with the clips below.

Monday night's show also saw a technical difficulty, when a piece of Taylor's set malfunctioned and briefly held her captive on a faux-balcony. The performer handled it with typical aplomb, joking, "I'll just be...here...forever, stuck up here, unless I choose to jump down." Then she invited the crowd to sing 1989 track "Clean" with her as they all awaited her liberation. A fan captured the minor hiccup, which you can watch below.


Lorde recently spoke to Lena Dunham about her and Taylor's friendship dynamic in an interview for Dazed Magazine. “She definitely brought me into this amazing world of supportive female friendship,” she said. “For me, someone starts talking about boys and I’m like, ‘I just don’t know what to say.’ I’m useless in that capacity and that was why I thought, ‘Well, I can’t have girl friends (because) I don’t know how to talk about boys.’ But Taylor just glosses over the fact that I’m terrible at that and she’s just like, ‘It’s OK, I’ll love you for your other qualities.’”

Watch another fan-captured video of the pals' July 13 performance below.