No - you can estimate a horse's age by looking at its teeth. Looking a "gift horse in the mouth" would be like judging the gift's value or appearing ungrateful. The general idea is: it may not be ideal (like an old horse) but it was free & you can still make good use of it & be grateful for having one at all.
It did not come from anywhere, the phrase should be 'Happy as a pig in muck/mud'. This creates an image of a pig rooting through a muddy field looking for roots/grubs in the ground which is their natural way of feeding.
adjective phrase
No. That phrase is a nonsense phrase which uses alliteration.
The prepositional phrase is from the zoo.
According to Thomas Tayler's Law Dictionary (printed in 1856), the phrase "Wolf's Head" pertains to an outlaw, meaning a person who might be killed with impugnity, like a wolf. It is said that the phrase was originally found in the phrase "to cry wolf's head." But I have no idea where that phrase came from.
According to Wiktionary, one of the possible origins of this phrase dates back to the legend of Medusa, who was the mythological being who could turn any creature or being into stone by just looking them in the eye.
The first occurrence of the phrase "I am legend" that I'm personally aware of comes from the Richard Matheson story "I Am Legend."
latin
The Bible
stop
from joey in friends
To fight with great determination or zeal.
1820-30
facebook entry
in concord and lexington.
England
from girls ...to hissy...