For the 17th year in a row, something incredibly bizarre has been happening on tube trains across the globe.
Travellers have been catching the tube, or subways as they’re largely known outside of the UK, without their trousers on.
No Trousers On The Tube Day, or No Pants Subway Ride Day, began in New York in 2002 and sees tens of thousands of people engaging in the silliness on the first Sunday of the year.
The trouserless tradition was started by a New York group called Improv Everywhere, with the idea being that random passengers would board trains at separate stops without their trousers on.
Participants would behave as if they did not know each other and still wear full winter clothing on their top half, to the bemusement of those around them – as the troupe explains in the video below.
Now cities across the world engage in the fun.
If you missed out this time, don’t worry it’ll be on again next year.
Just make sure you get the date right – this is an event that’s best not celebrated alone…