French New Year or Jour des Étrennes or Day of New Year’s Presents.
In France dinner parties are thrown for the entire family. People exchange presents and greeting cards. People began sending fake gifts on April first which originally culminated in the New Year feast of course these gifts were only as a joke on those who previously had received their étrennes or New Year's gifts, on that day.
Poisson d'avril or April fish is the name the French apply to one who is fooled or mocked on April first. Confectioners' windows display chocolate fish on this day and many friends anonymously send each other humorous postcards imprinted with pictures of fish.
The French adopted the reformed calendar in 1582 which changed the beginning of the New Year from March 25 to January first.