Taylor Swift continued her string of surprise 1989 tour guests last night (June 6) in Pittsburgh, PA when Little Big Town joined her on stage to sing "Pontoon."

Taylor sang along and linked arms with the quartet of country singers while the crowd went wild – check out video of the full performance via a fan in the audience:

But not all the action happened on stage – prior to the big concert reveal, Little Big Town serenaded the VIP room with "Girl Crush" (there may've been some interpretive dancing involved)...

...Tay snapped a photo with "Dance Moms" (and Sia music video star) Maddie Ziegler...

...then she mixed up Blink 182 lyrics with singers Vance Joy, Rachel Platten and Kelsea Ballerini...

...and basically, she turned the backstage area into one big singer-songwriter party.

Our invite must've gotten lost in the mail.