In England, there's a phenomenon called the "half-time kettle effect" where power use surges at half-time during England's matches in the World Cup as everyone turns on their tea kettles at the same time.
3
In October 1997, when Internet Explorer 4.0 was released, some Microsoft employees left a giant "From the IE team... We Love You" on Netscape's lawn.
9
In 1974, prankster Porky Bickar was so into April Fools, he flew hundreds of tires into a dormant volcano in Alaska and set them on fire - fooling the local populace and coast guard into thinking the volcano was active.
30
Colorado switched mile marker "420" to "419.99" to stop people from stealing it.
37
In Japan, more adult diapers are sold than baby diapers.
50