Do you know what tomorrow is?
In the USA it is April Fools Day and we play pranks like,
"Look out! There's a spider on your shoulder!"
The tradition in France includes poisson d'avril, attempting to attach a paper fish to the victim's back without being noticed. There is an interesting history of this holiday of foolishness, and it originated in France in the 16th century. You can read about it here.
Today in France, people who are fooled on April 1 are called poisson d'avril, which literally means the "April Fish," because a young naive fish is easily caught.
So, are you going to play a little prank tomorrow?
Marché d'Aligre et le Baron Rouge