The last "Saturday Night Live" of the year 2015 certainly ended with a bang, as musical guest Bruce Springsteen closed the show with a performance of "Santa Claus is Coming to Town" and was joined by an unexpected special guest.

Springsteen, the E Street Band and the other cast members who were already on stage welcomed Paul McCartney to join in on the performance of the classic Christmas song, complete with sleigh bells and backing vocals, according to Mashable.

"SNL" cast member Bobby Moynihan then posted a snapshot of himself together with the Boss, the legendary Beatle and his fellow cast members on Twitter after the appearance.

Besides the surprise closing performance, SNL also welcomed back former cast members Tina Fey and Amy Poehler back into the fold and helped host the last episode of the year over the weekend.

Springsteen and the band had performed "Meet Me in the City" and "The Ties That Bind" prior to the closing holiday-themed performance.

"SNL" will return on Jan. 16 with "Star Wars: The Force Awakens" villain Adam Driver hosting the first episode for 2016. Musical guests have yet to be announced, according to Variety.