Die Fledermaus (“The Bat”) is an opera by famous Austrian composer Johann Strauss II, the “Waltz King.” It’s always performed on New Year’s Eve because much of the storyline takes place at a traditional Viennese New Year’s Eve costume ball. The opera is sometimes called “The Revenge of the Bat” because the plot centers around Falke, who’s attempting to get back at his friend Eisenstein for leaving him dressed as a bat in the center of town after the previous year’s ball — a moment that made Falke the laughingstock of Vienna.