In 1957, the BBC show "Panorama" convinced Britons that Spaghetti was harvested from a "Spaghetti Tree".

This started as an April fool’s joke. It was presented as a 3 minute report for Panorama, a documentary programme that holds the record for the longest-running public affairs show in the world. The idea started when Charles de Jaeger, a cameraman from the show, remembered that teachers in Austria teased some kids for being stupid.

The joke was that if they were told that spaghetti grew on trees, they would believe it. The Britons believed the hoax with the help of a respectable voiceover and a well presented report. Also, because in 1950s Britain spaghetti was considered an exotic food and a rare delicacy.

An estimated 8 million people saw the report that day. Hundreds called the station the next day to ask for more information on how to cultivate them and others to question the authenticity of the story. The video is here, so check it out.

(Source)