A couple kiss as they shower in a mud pit near the main stage during the 21st Woodstock Festival in Kostrzyn-upon-Odra, Poland, July 31, 2015. An estimated 200,000 people attended the ongoing festival, a brainchild of Polish journalist and social campaigner Jerzy Owsiak, on Friday. Owsiak initiated the event to say thank you to those who donated money to his GOCC charity organisation that delivers medical care for children. (Photo by Kacper Pempel/Reuters)

Revelers dance and shout as they listen to music, in front of the main stage, during the 21st Woodstock Festival in Kostrzyn-upon-Odra, Poland July 31, 2015. (Photo by Kacper Pempel/Reuters)

Revelers dance and shout as they listen to music, in front of the main stage, during the 21st Woodstock Festival in Kostrzyn-upon-Odra, Poland, July 31, 2015. (Photo by Kacper Pempel/Reuters)

Revelers dance and shout as they listen to music, in front of the main stage, during the 21st Woodstock Festival in Kostrzyn-upon-Odra, Poland, July 31, 2015. (Photo by Kacper Pempel/Reuters)

A reveler dances as he listens to the music in front of the main stage during the 21st Woodstock Festival in Kostrzyn-upon-Odra, Poland July 30, 2015. (Photo by Kacper Pempel/Reuters)

A reveler dressed as Batman bungee jumps during the 21st Woodstock Festival in Kostrzyn-upon-Odra, Poland July 31, 2015. (Photo by Kacper Pempel/Reuters)

Vocalist Frah of Shaka Ponk performs as he jumps to the crowd from the main stage during the 21st Woodstock Festival in Kostrzyn-upon-Odra, Poland July 30, 2015. (Photo by Kacper Pempel/Reuters)

A general view of the main stage is seen during the 21st Woodstock Festival in Kostrzyn-upon-Odra, Poland July 31, 2015. (Photo by Kacper Pempel/Reuters)

A couple hugs near the main stage during the 21st Woodstock Festival in Kostrzyn-upon-Odra, Poland July 30, 2015. (Photo by Kacper Pempel/Reuters)

A man sleeps on a coach placed on the roof of a car during the 21st Woodstock Festival in Kostrzyn-upon-Odra, Poland July 31, 2015. (Photo by Kacper Pempel/Reuters)

A man shows his watermelon hat during the 21st Woodstock Festival in Kostrzyn-upon-Odra, Poland July 31, 2015. (Photo by Kacper Pempel/Reuters)

A bird's-eye view shows a camp site during the 21st Woodstock Festival in Kostrzyn-upon-Odra, Poland July 31, 2015. (Photo by Kacper Pempel/Reuters)

Revelers react as they listen to the music in front of the main stage during the 21st Woodstock Festival in Kostrzyn-upon-Odra, Poland July 30, 2015. (Photo by Kacper Pempel/Reuters)

A man with a mohawk attends the 21st Woodstock Festival in Kostrzyn-upon-Odra, Poland July 30, 2015. (Photo by Kacper Pempel/Reuters)

Revelers dance as they listen to the music in front of the main stage during the 21st Woodstock Festival in Kostrzyn-upon-Odra, Poland July 30, 2015. (Photo by Kacper Pempel/Reuters)

Revelers dance after taking part in beating the Guinness World Record of painted bodies in one time during the 21st Woodstock Festival in Kostrzyn-upon-Odra, Poland July 31, 2015. (Photo by Kacper Pempel/Reuters)

Revelers dance as they listen to the music in front of the main stage during the 21st Woodstock Festival in Kostrzyn-upon-Odra, Poland July 30, 2015. (Photo by Kacper Pempel/Reuters)