1 / 9Many travelers in London will not be wearing their trousers as they ride on the Elizabeth Line, which opened last year. The reason is: it's no trousers tube ride 2023, which is observed every year. 2 / 9 Passengers are seen on the subway trains with professional clothes on their upper halves but with only underwear, shoes and socks on their lower halves as they choose to ditch their pants.3 / 9The no trousers tube ride started twenty years ago and is said to have started in New York in 2002 by the comic performance art group, Improv Everywhere. 4 / 9The group says that the silly tradition began as a simple practical joke involving seven people who pretended not to see one another as they boarded a train at each station for seven consecutive stops.5 / 9It then became a global event which has been observed in more than 60 locations worldwide including London, Germany, France, Australia, Romania including Lisbon, Tokyo, and Toronto. 6 / 9However, it was no observed amid the Covid pandemic for the past two years. For 2023, the event was organised in London by the Stiff Upper Lip Society.7 / 9The only two requirements for anyone participating in the event is: participants must be willing to not wear their pants on the subway (obviously) and secondly, they should have a poker face while engaging in the event.8 / 9For Improv Everywhere, the purpose is absolutely nothing except random people, although dressed in winter jackets, hats and gloves, attend it without pants on a train.9 / 9The pictures from the traditional event are have gone viral on social media.