On Monday night the "1989" world tour rolled though Washington D.C.. Like most of her other shows, Taylor Swift brought along a special guest! The "Bad Blood" singer treated the crowd to a special performance with her BFF, Lorde. The two preformed Lorde's smash hit "Royals" at Nationals Park, Entertainment Weekly reported.

A photo posted by Lorde (@lordemusic) on Jul 13, 2015 at 11:12pm PDT

After the duet, the two best friends took to social media to gush about their love for each other.

"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," Lorde wrote on her Instagram.

The New Zealand native even wrote on her Twitter, "but seriously, @taylorswift13 is the leader of a great and beautiful galaxy that i'd live in forever."

"When your friend flies across the world to surprise your crowd with 'Royals' bc she's a wondrous angel. @lordemusic," Swift wrote on her Instagram, along with a picture of the two during their duet.