Turkey makes you sleepy. You only use 10% of your brain. You lose 40-45% of your body heat through your head. You can cure a hangover.
Popular wisdom is constantly fed to us day in and day out without anyone ever questioning it's origins, usually purported by a friend or acquaintance whom you believe only has every one's best interests in mind. The problem is that it is a rariety for someone to actually back up such a claim with any supportive evidence.
In a series of two articles published by the British Medical Journal, two professors known as Rachel C Vreeman and Aaron E Carroll have compiled a list of common myths that refute the claims at the beginning of this article with evidence and several sources. The articles are available here, as Part 1 and Part 2.
The reason for this article wasn't simply to link to an article, but to make a point. People (And I do mean anyone, academics and doctors as well as plumbers and housewife's) perpetuate claims that can be harmful or just useless without ever researching the origins of these claims. It is a silly and dangerous exercise, and yet we continue it without regard for the consequences of our action.
It is not primarily a human endeavour to misinform others that trust us, but it seems that individuals will actively repeat claims to others that have a modicum of respect for the individual as a way to actively define themselves in their own conscious, or simply to benefit themselves through an active exchange of supposedly helpful information. which explains why your doctor will tell you you need eight glasses of water a day, or why your grocier will always tell you the most expensive cheese is the healthiest.