Meaning: Define a threshold that can't be crossed without action or retaliation.
Example: Smoking is okay if you are outside, but I draw the line at smoking in public places.
Origin: Comes from one of the Psalms which contains a reference about "drawing a line in the sand" meaning to "proceed no further." It has been shortened to "draw the line."
Example: Okay, so the '72 Gremlin grandma gave you is not your idea of a babe magnet, but it was free - so don't look a gift horse in the mouth.
Origin: Horses have gum lines that recede with age. Hence older horses have longer teeth than young horses. To "look a horse in the mouth" is to examine the horse's mouth closely to determine its age (and therefore its usefulness and/or worth). To immediately judge a gift based on its worth or usefulness rather than the "thought" behind it considered rude, and ungrateful (it is a gift after all, and didn't cost the receiver anything).
The phrase is apparently quite old, a Latin version of it appeared in a work by St. Jerome in 420 AD, and it also exists in many languages. An Early english version (1510 AD) appears in John Standbridge's "Vulgari Standbrigi": "A gyuen hors may not (be) loked in the tethe."
Similarly, An older horse's teeth would be ground down from all the chewing. If the teeth were ground down, the animal would be less likely to be able to ingest enough food. In the wild, for many older herbivores death comes from malnutrition due to this inability to chew enough food. A person would look in the horse's mouth to see the amount of wear, and the subsequent age.
Apparently, there are also several other things that happen. One is that younger horses actually have more teeth. Another is that there is a certain age range (like 6-10 years) where the teeth actually have some circular bands. After this age range, the bands are worn away.
Hence you can tell a lot about a horse from inspection of the teeth.
Example: Don't be such a stranger. Drop a dime some time.
Origin: This is a good phrase to discuss with anyone born after 1970. Pay phones cost 50 cents today, but they really did cost 10 cents at one time. The dime was dropped into the slot of the pay phone.
Along similar lines is "to spend a penny" which in the U.K. means to use the toilet. The penny refers to the price of admission to a public pay toilet.
Example: New years eve is the one day of the year when people like to go out dressed to the nines.
Origin: Common lore has it that a tailor making a high quality suit uses more fabric. The best suits are made from nine yards of fabric. This may seem like a lot but a proper suit does indeed take nine yards of fabric. This is because a god suit has all the fabric cut in the same direction with the warp, or long strands of thread, parallel with the vertical line of the suit. This causes a great amount of waste in suit making, but if you want to go "dressed to the nines", you must pay for such waste.
Alternatively, The meaning is drawn from the phrase "the whole nine yards" which has come to mean a complete high quality job without cutting corners.
Alternatively, This saying originated in Shakespeare's time and is connected with the price a person had to pay for theater tickets depending on where their seats were located. The farthest seats were one pence and the ones closest to the stage were nine pence. If you sat in the expensive seats you would feel obliged to dress up so as not to look out of place with the other wealthy patrons.
Example: Beware any salesman that is dressed to a tea, smiles too much, and talks fast.
Origin: A short way of saying "dressed for a tea" or "dressed to go to a tea". In the Victorian era, high tea was a formal affair. All proper people dressed in appropriate attire.
