There are many traditions associated with April Fool’s Day, including relics from ancient rites of the vernal equinox, a farcical commemoration of Jesus’s trial, and the changing to the Julian from the Gregorian calendar, which moved New Year’s from April 1 to January 1. Those who refused to make the change were fools.
Modern April Fool’s Day is documented in England in the early 1700s. April Fool’s Day in the United States probably peaked in the 80s and 90s which Sun Microsystems staged elaborate hoaxes which were covered by the media. The Gaea Times.

This year, most people’s April First preoccupation is paying their mortgage.

An April fool in Denmark, regarding Copenhagen’s new subway. It looks as if one of its cars had an accident, and had broken through and surfaced on the square in front of the town hall. In reality, it was a retired subway car from the subway of Stockholm cut obliquely, with the front end placed onto the tiling and loose tiles scattered around it. Note the sign “Gevalia” and the accident site tape with the words “Uventede gæster?” (unexpected guests?). Gevalia coffee’s advertising featured various vehicles popping up with unexpected guests.