They were really in the buff and were participating in the annual World Naked Bike Ride.
If you happened to be taking in the sites in London and Manchester then you may have spotted the nude riders passing landmarks such as the London Eye and Big Ben.
This Video Contains Nudity
They were of all ages and some were even decorated in paint.
The festivities culminated in a big meeting at Hyde Park Corner where all the participants converged.
But there was a message behind the nudity.
It was meant to show the vulnerability of people on bikes who face dangers on the roads every day.
It was also a protest against the dependency on cars and of course participants also wanted to honour the human form.
The event also took place in other famous cities, including Mexico City and Toronto.
Meanwhile in America:
I Am Bored