People fight with pillows during World Pillow Fight Day in Vienna, Austria, April 2, 2016. REUTERS/Leonhard Foeger - RTSD9F0

People fight with pillows during World Pillow Fight Day in Vienna, Austria, April 2, 2016. REUTERS/Leonhard Foeger - RTSD9F2

Participants take part in International Pillow Fight Day in Kennington Park in south London, Britain April 2, 2016. REUTERS/Neil Hall - RTSD9ZX

People fight with pillows in front of the Brandenburg Gate during World Pillow Fight Day in Berlin, Germany April 2, 2016. REUTERS/Pawel Kopczynski - RTSD936

Participants take part in International Pillow Fight Day in Kennington Park in south London, Britain April 2, 2016. REUTERS/Neil Hall - RTSDA0M

Participants take part in the International Pillow Fight Day at Liberty Square, in Taipei, Taiwan April 2, 2016. REUTERS/Tyrone Siu - RTSD8FD

People fight with pillows during World Pillow Fight Day in Vienna, Austria, April 2, 2016. REUTERS/Leonhard Foeger - RTSD9E7

People fight with pillows during World Pillow Fight Day in Vienna, Austria, April 2, 2016. REUTERS/Leonhard Foeger - RTSD9F4

People fight with pillows in Pariser Platz during World Pillow Fight Day in Berlin, Germany April 2, 2016. REUTERS/Pawel Kopczynski - RTSD95L

Participants throw their pillows during the International Pillow Fight Day at Liberty Square, in Taipei, Taiwan April 2, 2016. REUTERS/Tyrone Siu TPX IMAGES OF THE DAY - RTSD8FC

People fight with pillows in front of the Brandenburg Gate during World Pillow Fight Day in Berlin, Germany April 2, 2016. REUTERS/Pawel Kopczynski - RTSD92L

People fight with pillows during World Pillow Fight Day in Vienna, Austria, April 2, 2016. REUTERS/Leonhard Foeger TPX IMAGES OF THE DAY - RTSD9ES

People fight with pillows during World Pillow Fight Day in Vienna, Austria, April 2, 2016. REUTERS/Leonhard Foeger - RTSD9F5

Participants take part in International Pillow Fight Day in Kennington Park in south London, Britain April 2, 2016. REUTERS/Neil Hall - RTSDA0E

People start to fight with pillows during World Pillow Fight Day in Vienna, Austria, April 2, 2016. REUTERS/Leonhard Foeger - RTSD9E5

People fight with pillows during World Pillow Fight Day in Vienna, Austria, April 2, 2016. REUTERS/Leonhard Foeger - RTSD9EZ

People fight with pillows during World Pillow Fight Day in Vienna, Austria, April 2, 2016. REUTERS/Leonhard Foeger - RTSD9F8

Participants take part in International Pillow Fight Day in Kennington Park in south London, Britain April 2, 2016. REUTERS/Neil Hall - RTSD9ZG

People fight with pillows in Pariser Platz during World Pillow Fight Day in Berlin, Germany April 2, 2016. REUTERS/Pawel Kopczynski - RTSD964

People fight with pillows during World Pillow Fight Day in Vienna, Austria, April 2, 2016. REUTERS/Leonhard Foeger - RTSD9EY

Participants take part in International Pillow Fight Day in Kennington Park in south London, Britain April 2, 2016. REUTERS/Neil Hall - RTSD9Z9

People fight with pillows in front of the Brandenburg Gate during World Pillow Fight Day in Berlin, Germany April 2, 2016. REUTERS/Pawel Kopczynski - RTSD999