Now here are some April Fool's jokes...
1998: Burger King published a full page advertisement in USA Today announcing the introduction of a new item to their menu: a "Left-Handed Whopper" specially designed for the 32 million left-handed Americans. According to the advertisement, the new whopper included the same ingredients as the original Whopper (lettuce, tomato, hamburger patty, etc.), but all the condiments were rotated 180 degrees for the benefit of their left-handed customers. The following day Burger King issued a follow-up release revealing that although the Left-Handed Whopper was a hoax, thousands of customers had gone into restaurants to request the new sandwich. Simultaneously, according to the press release, "many others requested their own 'right handed' version."
1976: The British astronomer Patrick Moore announced on BBC Radio 2 that at 9:47 AM a once-in-a-lifetime astronomical event was going to occur that listeners could experience in their very own homes. The planet Pluto would pass behind Jupiter, temporarily causing a gravitational alignment that would counteract and lessen the Earth's own gravity. Moore told his listeners that if they jumped in the air at the exact moment that this planetary alignment occurred, they would experience a strange floating sensation. When 9:47 AM arrived, BBC2 began to receive hundreds of phone calls from listeners claiming to have felt the sensation. One woman even reported that she and her eleven friends had risen from their chairs and floated around the room.
1974: Residents of Sitka, Alaska were alarmed when the long-dormant volcano neighboring them, Mount Edgecumbe, suddenly began to belch out billows of black smoke. People spilled out of their homes onto the streets to gaze up at the volcano, terrified that it was active again and might soon erupt. Luckily it turned out that man, not nature, was responsible for the smoke. A local practical joker named Porky Bickar had flown hundreds of old tires into the volcano's crater and then lit them on fire, all in a (successful) attempt to fool the city dwellers into believing that the volcano was stirring to life. According to local legend, when Mount St. Helens erupted six years later, a Sitka resident wrote to Bickar to tell him, "This time you've gone too far!"