Justin Timberlake & Jimmy Fallon have sign up for “Saturday Night Live” Christmas show Dec 21st! Jimmy is returning to host with his pal Justin Timberlake as his musical guest. It’s Fallon’s second time as “SNL” host — will happen on Saturday, Dec. 21. It will be Timberlake’s fifth time as a musical guest. Should be fun! They’re great together! Facebook here.