While Jimmy Fallon hosted Saturday Night Live on Dec. 21 and had Justin Timberlake as the night's musical guest, the dynamic duo was joined by several celebrity pals throughout the show.

The pair kicked off the show with a new take on Timberlake's classic Bring It On Down musical skits. They stuck with a holiday theme and dressed up as a giant roll of wrapping paper and his gift-bag buddy for Wrappinville. Timberlake and Fallon then showed off their impersonation skills in a Family Feud skit in which the late night talk show host played The Big Bang Theory's Jim Parsons and Timberlake playing Fallon.

When asked the Feud question of what someone would do to be sexy, Fallon (acting as a nerdy Parsons) suggested wearing a T-shirt that had on it the likeness of Japanese director-animator Hayao Miyazaki. Timberlake-as-Fallon gave a response to the same query that had everyone laughing -- including the real Fallon. He simply said, "Be Justin Timberlake."

Paul McCartney made a cameo during Fallon's monologue and other famous faces appeared for the latest installment of The Barry Gibb Talk Show - Madonna and Barry Gibb himself.

Watch Fallon's opening monologue below.

Fallon delivered his rendition of Baby It's Cold Outside with a clingy girlfriend twist.

Timberlake performed Only When I Walk Away and the acoustic tune Pair Of Wings.