For April Fool's Day pranks no one beats the BBC. Hands down, they're the most entertaining and creative pranksters.
For instance, there was the year that the new show, Panorama announced that because of a mild winter, Swiss spaghetti farmers had a bumper crop. Quite a few people called the BBC and asked about growing their own spaghetti tree, to which the BBC replied, "place a sprig of spaghetti in a tin of tomato sauce and hope for the best."
Then there was the year that they reported that an upcoming planetary alignment would decrease gravity and that listeners could experience it for themselves if they jumped into the air at exactly 9:47 on the morning of April 1st, 1976. Plenty of people tried it and called in to report that they'd experienced floating and some dude even complained that he'd hit his head on the ceiling and required medical attention.
Sadly, I can never think of anything funny enough or elaborate enough to pull off. So, I'll just rely on the BBC. Thanks, guys!
So what about you? What are your favorite April Fool's Day pranks?