Wonder if this has messed up a researcher or two? The custom of playing tricks on people on April 1 began in France after a new calendar was instituted in the 16th century. Previously, the New Year had been celebrated April 1, but the new calendar switched it to the familiar January 1. Out of habit, many people continued to observe April 1 as the beginning of the year. They were known as "April fools," and eventually the custom arose of playing tricks on that day. The French call victims of April Fools pranks "April fish." Maybe that's because they go for the bait. (Source: THE WORLD BOOK ENCYCLOPEDIA) Bob - K