Keep Calm and Carry On was a motivational poster produced by the British government in 1939 in preparation for the Second World War. It was encouragement for the British to keep their "stiff upper lip" in light of what was coming. In 2000, Stuart Manley, co-owner with his wife Mary of Barter Books Ltd. in Alnwick, Northumberland, was sorting through a box of used books bought at auction when he uncovered one of the original "Keep Calm and Carry On" posters. The couple framed it and hung it up by the cash register; it attracted so much interest that Manley began to produce and sell copies. Other companies followed suit, and the design rapidly began to be used as the theme for a wide range of products. Mary Manley later commented, "I didn't want it trivialised; but of course now it's been trivialised beyond belief." As the popularity of the poster in various media has grown, innumerable parodies, imitations and co-optations have also appeare...

While there are two different potential origins for this phrase one seems more plausible than the other. It seems that holding someone's nose to the grindstone was originally a form of punishment. And it wasn't literal, it was a figure of speech to indicate someone had been strapped to a workbench so that they had to work continuously. ( source ) Today we use it in a figurative way to say someone is working hard and without breaks.

Although there aren't any confirmed sources for this incredibly popular phrase all the theories circle around sports, of course! You can read about the varying ideas here . 

The original meaning of this idiom was very different than it is today - and that could be a good thing! It is said that back in the day , the medieval one, hunters would go out with big sticks and hit the bushes while making loud noises. The purpose was to scare any birds or animals hiding in the bushes. In retrospect, was that really such a good idea?  I mean, depending on what kind of animal might be hiding in the bush - would you really want to startle it and have it possibly charge you?! Anyway... These days it means avoiding the topic at hand or the answer to the question.

The meaning of this phrase seems pretty apparent. A dog that barks and barks and barks but never follows it through with an actual bite is not as scary as it may seem. According to Wiktionary  the phrase officially means: (idiomatic) Full of big talk but lacking action, power, or substance; pretentious, (idiomatic) Describes someone who often says cutting remarks, but actually has a soft personality underneath.

This idiom was tough to track down and I'm not sure anyone has ever done so successfully. But a smaller version of it, i.e. the whole six yards, was used in a newspaper article. You can view it here . How it came to mean "going the whole way" or similar sentiment is still a mystery.  I did find another short Q&A about the phrase. You can read about it here .

This common phrase means exactly what we use it for. Marriage. Why it means that is another story. There are several ideas about the why and you can read about them here .  I always liked the tradition of handfasting in a marriage ceremony.