‘It’s Always Sunny in Philadelphia’ Gave the Audience for ‘The Nightman Cometh’ No Warning for What They Were About to Watch

When the auditorium full of eager theater-goers filed in to watch Charlie Kelly’s magnum opus musical The Nightman Cometh, not one of them had any context for what they were watching or any way of knowing what insane twist would come next — least of all The Waitress.

By now, the It’s Always Sunny in Philadelphia Season Four episode “The Nightman Cometh” is such a massive cultural phenomenon that the titular musical itself has all but outgrown its humble beginnings. When the series stars and co-creators Rob McElhenney, Glenn Howerton and Charlie Day realized that the throwaway song performed by Dennis and Charlie in the Season Three episode “Sweet Dee’s Dating a Retarded Person” had become a bop in its own right and that fans were serenading each other with “Dayman / Aaa-aaahhhh / Fighter of the Nightman,” the idea arose to turn the gang’s failed single into a full-length stage production featuring the mythological figures introduced in the chorus.

As such, Charlie (Kelly) set to work “writing” a musical — that Artemis somehow transcribed it into the written word — and, in an elaborate ploy to win The Waitress’ hand in marriage, he tricked the gang into premiering one of the most beloved stage plays of the 21st century. Today, The Nightman Cometh is an actual stage musical that the Always Sunny cast has since taken on a sold-out tour, but back in 2008, the series needed an entire community theater’s worth of extras to fill the seats for reaction shots while filming the episode, and they made the wise decision not to warn any of the paid, confused background actors about what was to cometh.

“We spent days rehearsing the musical before we ever shot anything, rehearsing the music so that we had all the songs and all the staging down,” Howerton told GQ in a joint interview from 2018 about the history of the episode. The cast committed to preparing for the musical as if it was a real-life stage show, a process that helped them bring The Nightman Cometh to life in front of expectant audiences of Sunny fans the next year.

The episode’s director, Matt Shakman, elaborated, “We rehearsed on weekends, and then took a full day off in the middle of our shoot schedule — which is kind of unheard of in television — and just worked on how you would rehearse the play.” 

Shakman took on the role of a real-life theater director and producer and set to filling the house, explaining, “I wanted it to exist as a full theater piece, so I brought in 100 background performers who had no idea what they were about to watch and told the (cast), ‘Just do it all the way through.’ I got Artemis to act like the stage manager of the event and actually come out and do the speech that you always hear in shows about where the fire exits are.”

As for the edited-in laughter reactions to some of Mac’s moves in the episode, McElhenney said that the actual response from the audience was one of muted bewilderment. “The audience didn’t have any context, so I remember a lot of confused faces as we were performing,” he recalled, “People were wondering why it was funny. But I always go back to Glenn and Charlie; if they’re still laughing, then I know it’s funny.”

In fact, “The Nightman Cometh” was so funny that it became a cult phenomenon with a following larger than many entire sitcoms. Still, the lack of laughs from a completely confused crowd of extras never should have bothered McElhenney — he was going for gasps anyways.