Sorry - I didn't see you.

One of those things that "everybody knows" is that carrots are good for your eyesight.  Now it's a fact that carrots are a source of vitamin A, and that vitamin A deficiency can result in poor eyesight, but we in the Western world get plenty of Vitamin A from other sources, so where did this urban myth that eating carrots will enable you to see in the dark come from?  Well in fact it was a piece of government inspired misdirection in WW II to offer an explanation as to why our fighter pilots were so successful at shooting down German bombers at night - the real reason of course was our use of radar which back then was top secret.  So eat your carrots - but if you're out in the dark, best carry a torch!