April Fools' Day Pranks
While Americans will typically shout, "April Fools!" after pulling off a prank, Europeans sometimes refer to the holiday as "April Fish," as many observers will tack a paper fish to another's back and yell "April Fish!" However, the individual pranked is still referred to as the "Fool." Fish are often featured on European April Fools' Day cards. Traditional pranking often stops at midday in the United Kingdom, and if one pranks after this time, they themselves become the fool.
Hunt-the-Gowk Day is Scotland's version of the holiday, where one sends a messenger back and forth between another person, each time saying that they need to contact the other before the issue can be resolved. However, this practice is dying out in modern times. The Persian New Year falls on April 1st, which is marked in Iran with one of the oldest pranking traditions that still exist. This is actually another theater as to the holiday's origin.
Many other cultures celebrate April Fools' day similarly to the United States, and others may designate a "joke" day on another day of the year, such as May 1st for those living in Denmark.