It's the weekend!
And it's April Fools' Day. Wikipedia helpfully states "Although popular since the 19th century, the day is not a public holiday in any country." Geoffrey Chaucer's Canterbury Tales (1392) contains the first recorded association between 1 April and foolishness.

The custom of setting aside a day for the playing of harmless pranks upon one's neighbour is widely recognized. Some precursors of April Fools' Day include the Roman festival of Hilaria, the Holi festival of India and the medieval Feast of Fools!