Upright Citizens Brigade opens additional theater

But Saturday’s planned festivities were thrown for a further loop when rough weather prevented two of the founders, Matt Besser and Ian Roberts, from arriving in New York for the event (their plane from Los Angeles was diverted to Syracuse), leaving Ms. Poehler and the fourth member of the troupe, Matt Walsh, to handle M.C. duties for most of the night.

Some of the young faithful who turned out on Saturday night said it was actually a good omen that all four could not be together for the occasion. “It’s just too much explosive energy in one room,” said Cristina Cote, a sincere 24-year-old Manhattan resident and a student in the troupe’s improvisation and sketch-writing classes. “It would be like reuniting the Beatles.”

Instead, a sold-out 7:30 p.m. show featured Ms. Poehler, Mr. Walsh and Horatio Sanz, a “Saturday Night Live” alumnus, among a team of comedians who improvised sketches in response to monologues performed by the surprise guest Ian MacKaye, who formerly fronted the rock bands Fugazi and Minor Threat.

Responding to an audience member’s suggestion of the word “Medusa,” Mr. MacKaye recalled an incident when skinheads briefly overtook the stage at a rock show he played at a Chicago club called Medusa’s. That spawned skits about a janitor recruited to play Hamlet; an Appalachian folk band called American Taliban; and a balding middle-aged man who is mistaken for a skinhead. (“You people are strange,” Mr. MacKaye said from the stage.)

A second show at 9:30 offered a grab bag of acts that were, in theory, supposed to keep their sets to five to seven minutes. Sue Galloway, who plays an ambiguously accented comedy writer on “30 Rock,” performed a character piece about a drunken office worker singing an aggressive version of “I Will Follow Him” at a karaoke night; David Cross, the “Arrested Development” star, read remarks posted on the East Village blog EV Grieve that complained about the Upright Citizens Brigade’s arrival. (“Go back to campus, you new jack cornballs,” one outraged commenter demanded.)

Around midnight, when the show concluded, patrons and performers streamed into the bar to celebrate with fruit plates and bottled beer.

Mr. MacKaye, standing in the club’s narrow green room, seemed satisfied with his unlikely foray into comedy. “I’d never heard of it, I had no idea why I was asked,” he said of the Upright Citizens Brigade. “It was a very interesting, and, I think, healthy, pleasant experience. I was very happy to be invited. It totally felt natural, and it made sense to me.”

Upright Citizens Brigade TV episodes

Episode previews on Hulu