An artists performs on the street during a Myfest festival marking the May Day in the Kreuzberg district in Berlin, Germany on May 1, 2018. (Photo by Fabrizio Bensch/Reuters)

St Andrews University students skinny dip in the sea as May Day celebrations in St Andrews, Scotland on April 30, 2017. Hundreds of revellers ditched their clothes and bravely jumped into the bitterly cold North Sea. (Photo by Alamy Stock Photos)

The Acura Stage area is flooded after a storm dumped several inches of rain on the second Saturday of the New Orleans Jazz Fest at the Fair Grounds, Saturday, April 30, 2016. (Photo by David Grunfeld/NOLA.com/The Times-Picayune via AP Photo)

A Cambodian man sells shoes on a motorized cart travelling along a street in Phnom Penh, Cambodia, 30 April 2020. Cambodian authorities are enforcing strict traffic rules in an effort to cut down traffic accidents on the road as a new land traffic law will go into effect in the beggining of of May 2020. (Photo by Mak Remissa/EPA/EFE)

Two Brits enjoy Saturday night in Leeds, United Kingdom in bank holiday on May 1, 2021, as number of coronavirus cases and deaths keep decreasing in the UK. The government today reported seven new coronavirus deaths and a further 1,907 infections. (Photo by Nb press ltd)

An Armatix employee holds a “smart gun” by the company at the Armatix headquarters in Munich May 14, 2014. The gun is implanted with an electronic chip that allows it to be fired only if the shooter is wearing a watch that communicates with it through a radio signal. If the gun is moved more than 10 inches (25 cm) from the watch, it will not fire. A Maryland gun shop owner has dropped his plan to be the first in the United States to sell the so-called “smart gun” after a backlash that included death threats. (Photo by Michael Dalder/Reuters)

Participants ride horses, hold spears and wear historic armoured suits of the Middle Ages as they compete during the Saint George international knight tournament in Moscow, Russia, May 3, 2015. (Photo by Maxim Zmeyev/Reuters)

In this photo posted on Twitter, Sunday, May 3, 2015, and provided by NASA, Italian astronaut Samantha Cristoforetti sips espresso from a cup designed for use in zero-gravity, on the International Space Station. Cristoforetti, the first Italian woman in space, fired up the first espresso machine in space, which uses small capsules, or pods, of espresso coffee. (Photo by AP Photo/NASA)