I will have an April Fools party this Sunday. Shadowclans meeting at 7PM, Dinner served around 8PM, April foolery, bonfire, gaming, hot tubbing, dancing and stuff to follow.
New Years was held around April 1 until Pope Gregory 13 initiated the Gregorian calendar. Some places like England didn't bother to change the date of New Years and became "April Fools".
Eventually this fool's holiday evolved into pranking by sticking paper fish or signs on peoples' backs without their knowledge so they looked foolish.
This has evolved into playing pranks on people, such as nitrogen triiodide squirted in a keylock or the classic bucket full of acid propped above a partly open door. But these pranks are limited to being perpetrated only before noon on April first to limit revenge attacks for killed loved ones.