I'm a little bummed April 1st fell on a Wednesday this year, when I give private lessons instead of working at my schools. I'm sure I would have come home with a bunch of paper fish souvenirs.
In France April Fool's Day is pretty much the same as in the U.S. (kids tell lies, teachers trick kids into thinking there are tests, etc.) but instead of yelling out "April Fools," they say "poisson d'avril!" which literally means April fish.
One of my private lesson kids, right when I walked into his house, announced that France was going to change its national anthem because the current one is too violent. I stupidly believed him, until he shouted "POISSON D'AVRIL!" (But go ahead and Google a translation of the French national anthem, I wouldn't be surprised if eventually they stopped wanting to force kids to memorize lines like:
They come right to our arms
To slit the throats of our sons, our friends!
May impure blood
Water our fields!
All of these animals who, without pity,
Tear their mother's breast to pieces!
But anyways... I'll move on before I offend the French public)
The classic joke here is to try to stick a paper fish on other peoples' backs without them noticing. It's a bit odd and no one really knows where it came from. As much as I prefer my private lessons to my schools, it would have been funny to see everyone walking around with fish on their backs.