It is an international event. Pranksters were asked to converge at train stations wearing everything but their pants, and act nonchalant. Besides Chicago, No Pants rides took place in Washington, D.C., New York and Poland.
After the rides, participants met up at bars, also without pants.
The No Pants Ride got its start 10 years ago in NYC. The group Improv Everywhere says it has no political agenda; the goal is to get people to laugh.