The Wikipedia suggests the dozen may be one of the earliest primitive groupings, perhaps because there are approximately a dozen cycles of the moon or months in a cycle of the sun or year.” This, of course, then relates to the number of characters in astrology.
“Twelve is convenient because it has the most divisors of any number under 18. The use of twelve as a base number, known as the duodecimal system (also as dozenal), originated in Mesopotamia… Twelve dozen (12X12 = 144) are known as a gross; and twelve gross (12X12X12 = 1,728, the duodecimal 1,000) are called a great gross, a term most often used when shipping or buying items in bulk.
“A baker’s dozen, also known as a big or long dozen, is 13. Varying by country, some products are packaged or sold by the dozen, often foodstuff (a dozen eggs). Dozen may also be used to express a large number of items as in ‘several dozen’ (ex. dozens of people came to the party).”
The dozens is a slang term – which I’ve never heard – for “a ritualized game typically engaged in by two persons each of whom attempts to outdo the other in insults directed against members of the other’s family (usually used in the phrase play the dozens).”
Another definition I was not familiar with is “to talk incessantly.” Synonyms include prattle, blabber, run off at the mouth, and talk the hind legs off a donkey. Example sentence:
“She talks nineteen to the dozen, amusingly, self-deprecatingly, practically, irreverently.”
The term Dirty Dozen has several references, including:
Twelve less than desirable traits: in EWG’s 2016 Shopper’s Guide to Pesticides in Produce™, e.g.
The Dirty Dozen Brass Band is a New Orleans, Louisiana ensemble established in 1977. They show up on a couple cuts of my favorite Elvis Costello album, Spike. Here’s The Flintstones Meet The President.
The 1967 movie The Dirty Dozen I saw in a drive-in theater when I was a teenager. It had a cast of then and future all-stars including Lee Marvin, Ernest Borgnine, Charles Bronson, Jim Brown, John Cassavetes, Telly Savalas, Robert Webber, Donald Sutherland and George Kennedy.