Originating in the military, this slangy term began to be used during World War I and soon spread to civilian life. Several vulgar versions, such as chew someone's ass out, should be avoided in polite speech. HA! It basically means to rebuke harshly.

It’s not at all surprising that the origin of the idiom “bend over backwards” is in gymnastics. The term was used as early as 920 CE to compare the athletic act of back bending with an expenditure of effort to ensure that something went as planned. ( source ) Today the term has a slightly different meaning. It is usually used to describe accomplishing something difficult for someone and receiving no gratitude, recognition, or even in some cases acknowledgment for it.

There are a few different stories about how this phrase came into being and how it came to mean today's meaning - a large, possibly exorbitant, amount of money.  But back to possible origins of the phrase. One hails back to war times when amputees were paid a sum of money for limbs lost.  

It is originally a military term in which soldiers stand so close together that it is difficult to pass through them. ( source ) Today the term is used in a broader sense. Any kind of group of people, co-workers or congregants or political parties etc, that show support for each other publicly, especially when being criticised.

I couldn't find an origin for this phrase, I'm guessing it came into being over time. It means that a person is immovable in their behaviors, opinions, beliefs, etc. There are pros and cons to being set in your ways but it is usually meant in a negative way. Beware of being set in your ways - God can and will change it up.  (Proverbs 16:9)

The most interesting theory I found about the origin of this phrase was it popped up in the 1870s when slaves would hold dances mocking the mannerisms of their masters. The couple who won the contest would get a cake as their prize. Thus the dances became known as "a piece of cake" because it was so easy to mock their masters and win. HA! ( source ) So today when someone says, "That's a piece of cake" they are referring to the ease of which something can be done.

There's three options for this phrase and the most popular one seems to be about restaurant servers. Diners' wait-staff would get hopelessly behind and overwhelmed by orders, causing them to struggle as if they were walking through remarkably high weeds. Read about the other two thoughts on the phrase here .  Today the phrase has expanded to mean, in general, to be overwhelmed. I actually use it quite a bit. 

One theory on the origin of the phrase is that derives from the use of handbaskets in the guillotining method of capital punishment. And it seems that theory is pretty accurate from other accounts. Read more about it here . The phrase means something is rapidly deteriorating and/or is on course for disaster.

This one is pretty easy to figure out, it alludes to the uncontrolled way a loose axe-head flies off from its handle. It is first found in print in Thomas C. Haliburton's The Attaché; or, Sam Slick in England, 1843/4: "He flies right off the handle for nothing." Haliburton was an inventive writer and had a hand in the coining of several commonly used phrases: Ginger up Won't take no for an answer Today it means the same thing except in a figurative way - it means to lose control.

The origin of this common phrase is unknown - it just kind of appeared one day! You can read about it's appearance here . It's meaning is don't be ungrateful when you receive a gift.

Today's idiom started off as one phrase and morphed into how we use it today. The discovery of limelight and how it was used to put people in the center of attention is really interesting! ( source )

The word Ham to mean an "overacting inferior performer," apparently dates from about 1882 and originates from American English. Originally the word was hamfatter, meaning "actor of low grade," and has been linked to an old minstrel show song, "The Ham-fat Man" which dates from about 1863. Today when people ham it up they deliberately exaggerate their emotions or movements. ( source ) Here's my husband hamming it up in 1995. 

First used by the ancient Greeks this phrase refers to the risks that are shared by all the passengers in a small boat at sea. And today it means the same thing figuratively. It includes all people in similar, unpleasant circumstances on land, sea or in the air. ( source )

Around the beginning of the 20th century this idiom, and its variations, started appearing in conversation and print. It's meaning is rather clear - even if I were dead I wouldn't be caught...engaging in that activity, wearing that item, doing that thing, saying that, engaging with that person, etc. ( source )

Cows are notoriously languid creatures and make their way home at their own unhurried pace. That's certainly the imagery behind 'till the cows come home' or 'until the cows come home', but the precise time and place of the coining of this colloquial phrase isn't known. ( source ) These days the phrase is used to indicate something is taking a long time to happen or something will happen indefinitely.

Information on this idiom was/is elusive. This is all I got for today.  *Note to self: Do NOT Google XXX...

Benjamin Franklin has been credited with the origin of this idiom in some places but it actually showed up in the 17th century, in George Herbert's Outlandish Proverbs, circa 1633: A penny spar'd is twice got. It's meaning hasn't changed through the years and is quite clear, it is as useful to save money that you already have as it is to earn more. ( source )