In France today is called Poisson d'Avril, which means "The Fish of April". People cut fish shapes out of paper and put tape on the back and put them on chairs so people will sit on them and walk around with paper fishes on their bottoms all day LOL.
Last year after morning lineup we sent our 4th graders into the 5th grade rooms and the 5th graders into the 4th grade rooms.
This year I sent them into their reading classes.
Later, at lunch, I tried calling quiet time for a couple grades 5 minutes early. Knowing the 5th graders were onto me I told them they had been disrespectful this morning and would owe 10 minutes of their recess. We also convinced 2nd graders they would have extra reading homework on weekends from now on.
I was once given a love-type letter by a boy in high school on April Fool's Day. he even folded it into a heart. I wasn't sure if it was a joke or not until his friend(and mine at the time) confirmed it wasn't.
At my first job out of college I had a supervisor who loved playing April Fool's Jokes and she got me even though I was on to her. I was planning on taking the day off the next year, but she ended up leaving before then.
When I was a kid my best friend and her mom and brother told their dad there was a hole in the top of his car and he totally believed them.
I didn't play any tricks on my husband or cat. Darn!