Flash mob take over London Underground in their pants

A pretty standard commute on the tube, over-run with 150 participants in the worldwide, social-organised event 'No Pants Day' ('Trousers' for we Brits).

In it's eleventh year, No Pants Day started as a rather small, seven-person affiar in New York.  This year however, with the meteoric growth in social media campaigning via Facebook, Twitter and Youtube, event organisers 'Improv Everywhere' have managed to spread the demonstration to 60 cities across the globe including Madrid, Toronto, Mexico City and (pictured) London.  

"One of the things I love about the scope of the No Pants Subway Ride these days is that we really take over the whole system."  Improv Everywhere member, Charlie wrote in his blog post.

More than 16,000 people registered via the form set up on their site, to make for the most popular year yet, and some rather strange photography, as you can see from the videos below.