Sir Paul McCartney, Madonna and Barry Gibb showed off their comedic chops this weekend (21Dec13) by joining Justin Timberlake and funnyman Jimmy Fallon for a Christmas edition of U.S. sketch show Saturday Night Live.

Timberlake and Fallon kicked off Saturday's live gig by performing a medley of songs dressed as a tube of wrapping paper and a gift bag respectively, as they parodied tracks such as Ludacris' Roll Out (My Business), Gotye's Somebody That I Used To Know and It's Tricky by Run-D.M.C.

Fallon then delivered the opening monologue by showing off impressions of David Bowie, Bob Dylan and MCCartney as he acted out his dream collaboration, blaming heavy New York traffic for preventing the rockers from appearing in person.

However, as he began to mimic the former Beatle, MCCartney himself stepped out onstage, much to the crowd's delight, and quipped, "I was (stuck in traffic) but then I took a Citi Bike (public bike-sharing system). Am I too late to sing a song?"

The unlikely duo then launched into a rendition of Have Yourself A Merry Little Christmas as fake snow fell all around them.

MCCartney's unexpected appearance was just the first of many surprises - Madonna joined in a discussion about politics during spoof segment The Barry Gibb Talk Show, with Fallon sporting '70s attire, a fake wig and fake facial hair to portray the only surviving Bee Gees star.

The Emotions hitmaker appeared to be in on the joke as he joined Timberlake and Fallon, who were both rocking vintage hair styles and suits, to close out the skit.

Even outgoing New York City Mayor Michael Bloomberg made time for a cameo during Snl's Weekend Update to discuss his plans after stepping down from the post early next year (14).

Saturday Night Live will return to U.S. Tv screens for a new episode on 18 January (14) when rapper/actor Drake will serve as guest host.