Taylor Swift gave off serious Frozen vibes when she took the stage as Olaf, the snowman, during her 1989 world tour stop in Tampa, Florida, on Saturday. But the fun didn't stop there. For her latest round of surprise guests, Taylor brought out Idina Menzel, who was dressed as Elsa, for a performance of the movie's theme song, "Let It Go." Soon after, Taylor took to Instagram and shared a combination of photos and videos from her show, writing, "Frozen totally happened tonight. And 55,000 people sang 'Let it Go' so loudly, it nearly took my breath away. Good times, @idinamenzel." Check out Taylor's Halloween costume now, and then see even more celebrity getups from this year.