Day is the one day a year when mild psychological warfare is socially acceptable. No elaborate setups, no permanent damage—just harmless pranks that will leave your friends questioning their sanity while you try (and fail) to keep a straight face.

It’s almost that time of year, that day on the calendar that sparks either immense joy or general annoyance. April Fools’ Day. The holiday, which has had varied iterations across a number of western cultures over the centuries , is solidified in the United States, and specifically, in the nation’s schools.

This year, April Fools' Day falls on Tuesday, April 1. The origins of April Fools' Day date back to the 16th century, and came about when France switched from the Julian calendar to the Gregorian calendar. The calendar switch happened on April 1, 1563.