In one of my all-time favourite hoaxes, in 1957 the BBC managed to convince the British public that spaghetti grows on trees.
In the 1950s spaghetti was not widespread in Britain (it was “a bit exotic”), so the BBC programme Panorama filmed a hoax segment for April Fools Day.
The segment, narrated by veteran broadcaster Richard Dimbleby, showed a Swiss family harvesting spaghetti from trees, drying it in the sun, and then serving it up for dinner. All this was presented completely straight-faced, and viewers fell for it. Hundreds called in to the BBC to ask about acquiring their own spaghetti tree.