German who grew up in the 21st century here. The myth that eating lots of carrots will improve your eyesight/nightvision significantly is still more or less alive and well here.

As a millennial American, I was taught it as a child, and I'd estimate most people I know believe it to be true.

Blind Nazi after eating carrot.

Getting kids to eat their veg without complaining isn't a new problem.

maybe i'll call him turnip for a day. that might work

When the British were building the Mark I Landship (world's first "tank") it was a top secret project. However there were hundreds of civilian workers working on the assembly lines. Expecting that workers would start questioning about what they were building, the British war department told the workers that they were building "water carrying tanks".

Then since no popular formal name was given to the new armoured vehicles, the name "tank" stuck.