The day of the innocents is celebrated in Mexico and Latin America today. Originally celebrated to commemorate the day of the male children killed by King Herod, the day now has morphed into a similar custom as "April Fools Day."
Expect practical jokes. Wikipedia says "The mass media make jokes or distort their content in such a way that the information seems real...It is tradition that the newspapers publish whole pages of the humorous news...that seem serious and deceive the reader off guard."