from Lisa Winter, iflscience:
1. We only use 10% of our brains. It's true that there’s a great deal we don't know about the brain, but we certainly do know that we use our entire brain.
2. There is a dark side of the moon. Except in the case of a lunar eclipse, sunlight falls on half of the moon (exactly how half of Earth receives daylight at once) all of the time.
3. The full moon affects behavior. The topic has been studied many times over, and there is very limited correlation between the full moon and increased erratic behavior and certainly no causation discovered. While a few studies have indeed shown a spike in crime and the full moon, it was typically explained by falling on a holiday or weekend.
4. Sugar makes children hyperactive. Attending any child's birthday party where cake, ice cream, and sugary drinks about would make just about anyone a believer that sugar influences hyperactivity. There has not been much evidence to suggest that the so-called "sugar buzz" is actually real for children (aside from a small subset with an insulin disorder coupled with certain psychiatric disorders).
5. Lightning never strikes the same place twice. Lightning is a huge electrostatic discharge searching for a way down, and it isn't particularly interested in whether or not it has been hit before. In fact, lightning strikes the Empire State Building around 100 times per year.
6. Dropping a penny from a tall building will kill someone. Pennies are fairly lightweight at around one gram and being a flat circle doesn't bode well in terms of aerodynamics. Because it would tumble and flip the entire way down, its low mass and relatively low terminal velocity (105 km/h) wouldn't do much damage to the bystander on the sidewalk. It would feel similar to getting flicked in the head. Annoying, yes; but not lethal.
7. Hair and fingernails continue growing after death. However, skin and hair can appear to grow post-mortem. As the dead skin begins to dry out, they retract and pull away from the hair shafts and nail beds. The hair and fingernails are not affected by the lack of moisture and do not shrink, which can make it seem as if they had grown.
8. Cracking your knuckles gives you arthritis. While it makes sense on the surface that repeatedly pushing and stretching joints to make them crack would eventually lead to osteoarthritis, which is the painful deterioration of the joints, studies that have been performed on the topic have not been able to show a connection.
9. It takes seven years to digest swallowed chewing gum. The bulk of gum is made out of rubbery polymers known as elastomers along with glycerin and vegetable oil-based ingredients to keep the gum soft and moist. Once the body has extracted what little it can from the gum, the rest is passed along as waste, just like anything else.
10. Antibiotics kill viruses. This one pops up every cold and flu season. Antibiotics, by their very definition, kill bacteria. The common cold and influenza are viruses and are not affected by antibiotic use.
The details can be found here.