You may be familiar with it -- it's called the "frozen pants challenge," and it couldn't be more appropriate as temperatures in the Midwest are frigid right now.
On Tuesday at the zoo, the frozen pants challenge manifested as a frozen zoo uniform making stops in front of various animal habitats.
The frozen clothing paid visits to animals that can tolerate the cold pretty well.
They included the bison, a polar bear, Bactrian camels, llamas, and one of the California sea lions.
Oh, and let's not forget the iconic south gate lion statues - the frozen pants showed up there too.
West Ridge man uses frozen pants to call dibs on parking spot
The zoo got the idea after a Chicago used the unique idea to claim parking dibs during the recent frigid weather.
Adam Selzer had a little fun when his pants were spotted on standing in his West Ridge neighborhood.
He didn't really use the frozen pants for dibs but they certainly could be.
You can join in on the fun too! It's easy! You just get a pair of pants soaking wet, then freeze and mold them out in the cold.