April 1 may be best known as April Fools Day, but it also has another, equally frivolous significance.

Because the first day of the fourth month is celebrated around the world as International Pillow Fight Day.

According to website pillowfightday.com , the key rules are to swing lightly, only use soft pillows and remove glasses before beginning.

The site lists around 40 cities where pillow fights are expected to take place on April 1, 2017.