Greg Hess, Mark Raterman, and Brendan Jennings Credit: Courtesy Cook County Social Club

On the first-floor stage of iO Theater eight years ago, the members of Cook County Social Club started performing scenes about fellatio. Why? It’s unclear. Cook County Social Club moves at lightning speed—troupe member Brendan Jennings got on his knees without hesitation, ready to perform stage fellatio on Mark Raterman, as per the scene’s needs, and Raterman immediately turned around and dropped trou.

Cook County Social Club consists of Jennings, Raterman, Bill Cochran, Greg Hess, and Tim Robinson (who was a cast member on Saturday Night Live for one season). But really it’s a shameless, fast-paced hive mind. Make no mistake: When Jennings says the word “fellatio” onstage he knows Raterman is going to take off his pants, not just mime it. And he knows he’ll have two seconds to prepare.

The group’s members come across as best friends. New jokes or scene concepts register as playful one-upmanship, trying to take someone else’s idea all the way to its absurd conclusion. Mundane details are never ignored, and often become through lines for an entire show. The crew don’t care who had the idea, so long as they can fuck with it.

Cook County Social Club performed every Tuesday night at iO’s old Wrigleyville location, where the Cook cult was strong. Shows routinely sold out, and the Reader awarded the quintet “Best improv group” in 2010. They even started offering improv classes independent of any one theater. Now, for a single evening, the new iO Theater hosts a Cook County Social Club reunion. Expect tickets, and the show, to go fast.

Cook County Social Club Fri 11/12, 8 and 10:30 PM, iO Theater, 1501 N. Kingsbury,, $20.