UPDATE (7/20): Gordon makes Second City appearance two days running.
According to a report posted to phantasytour.com (hat tip @PTThreadOfTheDay), Phish bassist Mike Gordon found his way to the stage at Chicago's famed Second City improv theater on Thursday night before Phish's 3-Day Chicago run.
A poster in the thread indicates that Gordon was enjoying the show with his wife when he was invited up on stage. "He told embarrassing stories about Phish and they [Second City Performers] based scenes on them".
One photo has emerged via @carolynwitsake on Instagram, but as of yet, no video.