April Fool's Day.
The first mention of this custom is a curt note in Aubrey: ‘Fooles holy day. We observe it on ye first of April. And so it is kept in Germany everywhere.’ ( Aubrey, 1686, 1880: 10). It must have reached England from Germany or France in the mid-17th century, and quickly became very popular under the name All Fools' Day; 18th-century writers call it ‘universal’. At this period it was an adult amusement; people tried to trick one another into going on ridiculous errands, seeking nonexistent objects such as pigeon's milk or a biography of Eve's mother, and so on.
Individual hoaxing of this kind grew rare among adults in the 19th century, but ...