Jimmy Fallon turned up to host “Saturday Night Live” this weekend, taking a week off from his NBC late-night show and basically walking across the hallway at 30 Rock to return to his old “SNL” stomping grounds.

The show he guest-hosted on the weekend before Christmas was a combination of old and new — much of it celebrating his formidable talent for comedy, impersonations, music and anything else you need done when you’re producing a variety show.

But there’s more to Jimmy Fallon than equine mimickry. In a bit with singing star Michael Buble on Saturday night’s show, Jimmy imitated Sting and Justin Bieber.

But when the laughter stops and Jimmy is alone in his dressing room, what’s he really thinking about? Who — or what — does he talk to when he wants to contemplate his innermost thoughts? The answer: His mirror!