Some people love today. Others loathe it. Oh come on, have a sense of humor! Can't you hear people saying that to you? But being the butt of a joke can be downright unfunny. Who thought up a silly day like today?
Well, it could come from ancient Rome, whose citizens celebrated "Hilaria" on March 25th, with mocking others - including government officials - and playing games or masks. The arrival of spring always gives a sense of "renewal" and why not have fun after a long, dreary winter?
It's also possible that the Catholic Church had a hand in the fun, with its "Feast of Fools" on or around January 1st during medieval times. People in England and France dressed in costumes, with the lowborn appearing as kings or queens as well as the reverse, leading animals into churches, hanging paper tails on people. And then Pope Gregory XIII issued a decree in the late 1500s about adopting a standard calendar in Christian countries. The old Julian one was replaced by the Gregorian one - moving the new year from the end of March to the first of January. Hey, not everyone found out via the Internet or Facebook in those days! So the people who kept "feasting the fools" were called “April fools.” Or some such nonsense.
In France, it was great fun to slap a paper fish on friends' backs and yell "Poisson d'Avril"! Oh, sure. Real fun. I suppose it's better than "Kick Me", but still.
The first documented "prank" was in 1698, when the Tower of London posted a sign. No joke! Oh, there were lions in the menagerie. But no washing.
Over the years, more and more people got into the "game" of pranks -- here's a website with the TOP TEN APRIL FOOL'S JOKES OF ALL TIME. There's actually 100, but I figured you'll be so busy with pulling your own pranks you only have time to read ten. If you're fooling around today (get it?), then check them all out - like Alabama changing the value of Pi, finding the body of Nessie, the comic strip switcheroo, flying penguins, canned unicorn meat, Big Ben going digital, Viagra for hamsters, and the Swiss mountain cleaners. HA. Great list. You can't make this stuff up.
The video below, the "Swiss Spaghetti Harvest", actually was shown on a BBC news show in 1957.