Have you ever been told that eating carrots will improve your eye sight? Then congratulations, you've just been fed propaganda from a very successful, but very silly British propaganda campaign.
During the Battle of Britain, the Germans started noticing that a bunch of their planes were getting shot down in instances where the British shouldn't have seen them coming. It was almost like they had some sort of radio device that could detect the presence of incoming objects -- actually, it was exactly that: Britain had perfected the radar and didn't tell anyone about it. Obviously the Brits couldn't let the Germans know they had access to this new technology...British papers published a story about a RAF pilot called John "Cat Eyes" Cunningham who had shot down 20 enemy planes thanks to his superhuman night vision, an ability he achieved by eating lots of carrots.
While carrots are good for your eyes, they can't actually improve your eyesight and they certainly can't give you night vision. Even so, many people still believe that munching them down like Bugs Bunny will help them get rid of their glasses all because of a propaganda campaign.