People travelling on the Minneapolis Light Rail system got something of a shock this month when a group of fellow commuters suddenly all began taking off their trousers.
The pant-less passengers had boarded specifically to take part in a trouser-less demonstration as a part of the city's fourth annual No-Pants Light Rail Ride.
After unpopping their flies and unzipping their zippers, the pant-less participants then just acted as they would normally do on any normal commute - talking on their mobile phones, chatting to fellow passengers and enjoying the odd game of Angry Birds. Only without any trousers on.
The organisers said it was all meant to bring a little strangeness into the routine and tedium of the day, and there's no doubt that it did. They also said that the display was not meant to be indecent or offensive or anything and that thongs and banana hammocks were therefore strictly forbidden.
I understand the idea for the demonstration came orginally from the brilliant New York mass improvisation group Improv Everywhere, who have been doing No Pants Subway rides (and much else besides) for some time.
It's mad, of course, but essentially harmless - which is possibly more than can be said for some of the activities on Minneapolis's Light Rail system at times.
However, one crucial question remains.
What exactly is a banana hammock?