In a new behind-the-scenes teaser for the movie that dropped Monday, Swift marvels, "If you told me I was gonna get to be a cat for work? What?!" The minute-long clip opens with Swift practicing her dance moves as sexy cat Bombalurina before moving on to co-star James Corden, who admits, "You're gonna take a load of people and they're gonna pretend to be cats. If you just say it out loud, it's bonkers."Cats--which also stars Jennifer Hudson, Idris Elba, Rebel Wilson, and Jason Derulo--purrs into theaters on December 20th.