It’s been more than a decade since the Upright Citizens Brigade—better known as UCB—decamped for greener pastures in New York, and subsequently Los Angeles. But no one has forgotten their Chicago roots. On Tuesday, founding members Matt Besser, Ian Roberts, Horatio Sanz and Matt Walsh bring “ASSSSCAT,” UCB’s signature “fuck-around” show, to the Lakeshore Theater.

Similar to the Armando Diaz Experience (Monday nights at i.O.), an audience suggestion sparks a monologue, which inspires a succession of scenes. I recently spoke with Matt Besser, now based in L.A., who told me the long and sordid story behind the show’s name—a tale of beer and belligerence.

“We were doing a show at the Elbo Room once with some of UCB buddies, and we ended up bringing in our own beer (which was very uncool to the Elbo Room) and getting really drunk before the show started. And then we started improvising and it was going terribly. They were hating us. And at some point I was just on stage by myself, ‘cause the other guys were sick of stepping on stage on and bombing. And I was making my igloo, or some scene like that, and Horatio Sanz just started yelling, ‘ASS CAT!’ And then someone on the other side of the stage started yelling, ‘ASS CAT!’ And I was like, fuck this, and I walked off stage. Now there’s an empty stage with all the improvisers drinking beer and screaming ‘ASS CAT’ across the stage to each other while the audience was going, ‘What the fuck did I pay for? What the hell’s going on here?’”

Ever since “that became the term we used any time we were improvising or doing any kind of show where we were disregarding the audience completely. So it became known as a show where we would just fuck around. And when we started in New York, that was kind of our fuck-around show,” when they weren’t working on episodes of “Upright Citizens Brigade,” the sketch comedy series that ran on Comedy Central from 1998-2000. (September 18 marks the DVD release of season two.)

The Lakeshore hopes to take advantage of UCB’s name recognition and talent pool. Starting this month, Tuesdays are given over to UCB acts, including Besser himself, who returns on October 9 with his one-man show, “Matt Besser’s Magical Sack of Dump.” In it, he plays various characters, including a Nazi Pope who you can find on a Funny or Die segment called “Ask the Pope” telling a porn star: “You are just a dick with a man on the end of it.” (Nina Metz)

The Upright Citizens Brigade performs throughout the fall at the Lakeshore Theater, 3175 North Broadway, (773)472-3492.