Justin Theroux makes surprise appearance on Saturday Night Live

Justin Theroux has made a hilarious cameo appearance on Saturday Night Live opposite cast member Kyle Mooney.

The actor, 48, turned up on the show’s Leap Day episode to help 35-year-old comedian Kyle get himself in shape.

In the sketch, Beck Bennett, 35, and host John Mulaney, 37, join Kyle – playing themselves – as they try to devise a routine for that week’s SNL.

Surprise star: Justin Theroux has made a hilarious cameo appearance on Saturday Night Live opposite cast member Kyle Mooney

But after being left out of a proposed sketch about male strippers, because he is always typecast as the ‘dork’, Kyle decides to get buff.

With the help of guest star Justin and a nutritionist, the comedian sets up a personal gym in his office, and becomes more ‘attractive’ to his co-workers by piling on muscle.

Kyle showed up two days later with bulging biceps and a chiseled chin after putting on 37lbs of muscle — in two days — so that he could star in a male strip club sketch John was writing.

Feel the burn: The actor, 48, turned up on the show's Leap Day episode to help the 35-year-old comedian Kyle get himself in shape

Feel the burn: The actor, 48, turned up on the show’s Leap Day episode to help the 35-year-old comedian Kyle get himself in shape

But after extensive rewrites, John only wants dorks in the sketch and so beefcake Kyle is cut again, and then fired from SNL for good measure.

The long-running sketch show saw former writer John Mulaney return as host for a third year in a row, and was joined by Jake Gyllenhaal, 39, to provide some star power.

Mulaney played to his strengths in the monologue with a hilarious stand-up set featuring tangents about how terrible men are at making friends and the idiosyncrasies of the Bill of Rights.

Hilarious: After being left out of a proposed sketch about male strippers, because he is always typecast as the 'dork', Kyle decides to get buff with the help of 'trainer' Just Theroux

Hilarious: After being left out of a proposed sketch about male strippers, because he is always typecast as the ‘dork’, Kyle decides to get buff with the help of ‘trainer’ Just Theroux

Awkward: But after extensive rewrites, John only wants dorks in the sketch and so beefcake Kyle is cut again, and then fired from SNL for good measure

Awkward: But after extensive rewrites, John only wants dorks in the sketch and so beefcake Kyle is cut again, and then fired from SNL for good measure

The comedian was on screen from the opening sketch, about a press conference on the COVID-19 coronavirus that was derailed by the Democratic presidential primary candidates, in which he played a vaudeville-style Joe Biden.

Fred Armisen, Rachel Dratch and Larry David also guest-starred as former NYC Mayor Michael Bloomberg, Senator Amy Klobuchar and Senator Joe Biden.

After the break, John starred in a TCM segment of ‘Fiddler On The Roof for W.A.S.P.s, The Sound Of Music.’

Laugh riot: John played to his strengths in the monologue with a stand-up set featuring tangents about how terrible men are at making friends and the idiosyncrasies of the Bill of Rights

Laugh riot: John played to his strengths in the monologue with a stand-up set featuring tangents about how terrible men are at making friends and the idiosyncrasies of the Bill of Rights

Double trouble: Jake Gyllenhaal, 39, added some surprise star power to Saturday Night Live as comedian John, 37, had a hilarious third time hosting

Double trouble: Jake Gyllenhaal, 39, added some surprise star power to Saturday Night Live as comedian John, 37, had a hilarious third time hosting

He played the Nazi boyfriend of the eldest von Trapp daughter, played by Cicely Strong.

During a performance of Sixteen Going On Seventeen, he revealed he was actually in his forties, which seemed to worry her a bit more than the Nazi thing.

‘In a few months, this will be the least of your worries,’ he joked.

Hit the ground running: The comedian was on screen from the opening sketch, about a press conference on the coronavirus that was derailed by the Democratic presidential candidates

Hit the ground running: The comedian was on screen from the opening sketch, about a press conference on the coronavirus that was derailed by the Democratic presidential candidates

Classic: After the break, John starred in a TCM segment of 'Fiddler On The Roof for W.A.S.P.s, The Sound Of Music'

Classic: After the break, John starred in a TCM segment of ‘Fiddler On The Roof for W.A.S.P.s, The Sound Of Music’

Toxic relationship: He played the Nazi boyfriend of the eldest von Trapp daughter (Cicely Strong).

Toxic relationship: He played the Nazi boyfriend of the eldest von Trapp daughter (Cicely Strong).

John was back for the next sketch, as the father of a daughter who was celebrating that she just got accepted into Stanford.

He lost his temper on his nephew (played by Pete Davidson) after he created a meme from his Facebook profile photo.

He put on a slideshow of the memes full of gratuitous self owns in front of his own family.

Brutal: John was back for the next sketch. He lost his temper on his nephew (Pete Davidson) after he created a meme from his Facebook profile photo

Brutal: John was back for the next sketch. He lost his temper on his nephew (Pete Davidson) after he created a meme from his Facebook profile photo