Coach After Dark: Sports Gear Disco

Hi guys, I am coming to Chicago in the next few days and I see there is an event at Jackhammer called Coach after dark - sportsgear disco. In the description they specify that singlets/sportsgear are not required by encouraged, but I was wondering if anyone has been before wearing singlets/lycra/sportsgear or whether it is the usual type of event where most people will just be in jockstrap or regular clothes? Here is the link: https://www.eventbrite.com/e/coach-after-dark-chicago-tickets-1987165553664