Jimmy Fallon, Paul McCartney and "Sing" Cast Perform "Wonderful Christmastime" (A Cappella)

Perfecto!...

Jimmy and The Roots join Paul McCartney, Matthew McConaughey, Reese Witherspoon, Scarlett Johansson, Seth MacFarlane and Tori Kelly for an a cappella rendition of "Wonderful Christmastime."

The Tonight Show Starring Jimmy Fallon