The moment happened during Swift's Halloween concert in Tampa, Florida, where she performed her "1989" tune "Style" dressed as the animated flick's goofy snowman. Shortly after, Menzel -- decked out in an ice blue replica of Elsa's signature gown -- joined the songstress on stage to belt out part of "Let It Go."
"Frozen totally happened tonight," Swift later wrote on Instagram of the awesome, showstopping performance. "And 55,000 people sang 'Let it Go' so loudly, it nearly took my breath away."
Swift is notorious for parading around her famous pals during her "1989" tour, but it makes sense that she'd want to incorporate "Frozen" in some way -- after all, her album was huge, and so was "Frozen," and there's no doubt lots of overlap in each's core audiences. Check out a quick video of the fun below.
Photo credit: Taylor Swift/Instagram