Two attendees compete in the biggest vape cloud competition at the Vape Summit 3 in Las Vegas, Nevada May 2, 2015. According to new research provided to Reuters, youngsters say that performing tricks is one of the top two reasons they began using e-cigs. (Photo by David Becker/Reuters)

A meteorite burns up in the atmosphere as seen in this photo taken near of Salgotarjan, 109 kms northeast of Budapest, Hungary, late 21 April 2015. The Moon and Venus can be seen on the left. (Photo by Peter Komka/EPA)

An altar is pictured after it was decorated by the Antar family with some 3,000 traditional cheese and corn buns called “chipas”, in celebration of Kurusu Ara in Asuncion May 3, 2015. Kurusu Ara, the Day of the Cross, is a Catholic festival that is combined with local Gurani culture and falls annually on May 3. Paraguayans typically celebrate the festival with chipas, used to decorate religious shrines and altars. The chipas are later distributed to attendees. The buns at the top are arranged to read, “March 3 live”. (Photo by Jorge Adorno/Reuters)

A child rescued from Boko Haram in Sambisa forest is seen at the Internally Displaced People's camp in Yola, Nigeria May 3, 2015. Hundreds of traumatised Nigerian women and children rescued from Boko Haram Islamists have been released into the care of authorities at a refugee camp in the eastern town of Yola, an army spokesman said. (Photo by Afolabi Sotunde/Reuters)

Participants compete during the Strong Race event near Tukums, Latvia, May 3, 2015. More than 4,000 people participated in this 9 km endurance race with 33 different obstacles. (Photo by Ints Kalnins/Reuters)

A man smokes marijuana during a demonstration in support of the legalization of marijuana in Medellin, May 2, 2015. (Photo by Fredy Builes/Reuters)

A competitor participates in the Tough Mudder challenge near Henley-on-Thames in southern England May 2, 2015. (Photo by Eddie Keogh/Reuters)

A reveller walks through the streets in the early hours during traditional May Day celebrations in Oxford, Britain, May 1, 2015. (Photo by Dylan Martinez/Reuters)