Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.

Cracking your knuckles (or any of your joints) can have therapeutic benefits. When you crack one of your joints you are pulling the bones that are connected at the joint apart from each other. This process stimulates your tendons, relaxes your muscles, and loosens your joints. Chiropractors do this for spinal joints when your back is sore and stiff, but you can do this on your own for your knuckles, toes, knees, neck, etc.

Unfortunately, there can be too much of a good thing. Cracking your knuckles will never lead to arthritis (despite what your mom keeps telling you), but scientists have discovered that it can cause tissue damage in the affected joints. Knuckle-cracking pulls your finger bones apart which stretches your ligaments. Too much stretching of your ligaments will cause damage to your fingers akin to the arm injuries sustained by a baseball pitcher who throws too many pitches. In addition to making your hand really sore, this ligament damage can also result in reduced grip strength.

How does this work? Your joints, the places in your body where you can bend, are where your bones intersect and are held together by ligaments. These joints are surrounded by a liquid called synovial fluid. When you stretch your ligaments by pulling the bones apart to crack your knuckles a gas in the synovial fluid escapes and turns into a bubble. This process is called cavitation. Cavitation ends when the bubble eventually bursts, producing that popping sound we know and love. After that, your joints won't be able to crack for another 25-30 minutes while the gas gets reabsorbed into the synovial fluid.

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There are weird similarities between Abraham Lincoln and John F. Kennedy.

• Abraham Lincoln was elected to Congress in 1846. John F. Kennedy was elected to Congress in 1946.
• Abraham Lincoln was elected President in 1860. John F. Kennedy was elected President in 1960.
• Both were shot in the back of the head in the presence of their wives.
• Both wives lost their children while living in the White House.
• Both Presidents were shot on a Friday.
• Lincoln's secretary was named Kennedy.
• Both were succeeded by Southerners named Johnson.
• Andrew Johnson, who succeeded Lincoln, was born in 1808. Lyndon Johnson, who succeeded Kennedy, was born in 1908.
• Lincoln was shot in the Ford Theatre. Kennedy was shot in a Lincoln, made by Ford.
• Lincoln was shot in a theater and his assassin ran and hid in a warehouse. Kennedy was shot from a warehouse and his assassin ran And hid in a theater.
• Booth and Oswald were assassinated before their trials.

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Having sex while sick can reduce a fever due to the sweat produced.

Everyone knows that sex is enjoyable. More than that, there are many other benefits to sex beyond just the fact that it is fun. One is that it can help with a fever. Sex works as a natural antihistamine that combats fever and even asthma.

There is a lengthy list of other health benefits as well. Women’s bodies produce more estrogen when they’re having sex making their hair shinier and their skin softer. Sex also burns calories and strengthens muscles.

It also sharpens senses and acts as a natural painkiller. Levels of the hormone oxytocin rise and release a deluge of endorphins. These endorphins calm pain that results from any number of maladies, from migraines to arthritis.

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Anatidaephobia is the fear that somewhere in the world there is a duck watching you.

Anatidaephobia is the pervasive, irrational fear that, somewhere in the world, a duck is watching you. The person believes that no matter where they are or what they are doing, a duck is watching them.

The people who suffer from this phobia have suffered some sort of trauma in their lives, likely when he or she was a child. This trauma probably had to do with a duck or some sort of related water fowl, like a goose. Perhaps the person was attacked by one of these animals.

Some of the symptoms of this phobia include an anxiety or panic attack. This results in a dry mouth, shortness of breath, muscle tension, hyperventilation, etc.

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Four is the only number that has the same amount of letters as its actual value