Jimmy Fallon Recruits Paul McCartney and the Sing Cast to Get You in the Christmas Spirit

Jimmy Fallon and his famous friends are here to help get you in the Christmas spirit!

The Tonight Show host gathered Paul McCartney, The Roots and the cast of Sing -- including Matthew McConaughey, Reese Witherspoon and Scarlett Johansson -- to perform an a cappella version of McCartney's holiday hit, "Wonderful Christmastime."

The video begins like many of Fallon's previous star-studded performances with each of the stars singing their part straight-to-camera in front of a colorful background.

But soon enough, the stars are decked out like real Christmas carolers -- that is, until they all transform into the adorable animal characters from the animated musical Sing, because nothing says Christmas like a singing koala.