This is one of the most popular and entertaining Christmas traditions in Spain. December 28 is the day when everyone is allowed to play practical jokes and when it is customary to buy joke articles in Christmas markets like the one in the Plaza Mayor square in Madrid.

This celebration appears to have its origins in an event narrated by the Bible concerning King Herod and the innocents, although over the centuries it has evolved to become a boisterous day in which even the media usually reports on some outrageous and completely invented news story.

One of the most widespread jokes on this day is to stick a figure cut out of white paper on someone's back (without them realising). The word in Spanish for this practical joke is an "inocentada". And, in the numerous Christmas markets (usually located in the large squares in the cities) you can find a whole range of joke articles (wigs, itching powder, false ink…).

Many areas in Spain also have other typical local celebrations on 28 December. Examples include the festivity of Los Locos (or "lunatics") in Jalance (in Valencia, the mayor of the lunatics governs the town for 24 hours); the festivity of the Holy Innocents in Nogalte (in Murcia, with popular dancing and bands of singers); the Danza de Los Locos, or "dance of the lunatics" in Fuente Carreteros (in Cordoba); the "Obispillo", or "little bishop" (celebrated in places such as Burgos, Palencia and Murcia, where a small boy is chosen to carry out the functions of the bishop for one day); and the "Festa dels Enfarinats" de Ibi (in Alicante, involving a "battle" fought with eggs, flour and firecrackers).