= new reply since forum marked as read
in a variety of cultures for centuries - for example, Norse, old English, Celtic, Inuit, Arabic, ancient Greek, Japanese and Finnish. https://en.wikipedia.org/wiki/Flyting "The exchanges would become extremely provocative, often involving accusations of cowardice or sexual perversion."... "Flyting is similar in both form and function to the modern practice of freestyle battles between rappers and the historic practice of the Dozens, a verbal-combat game representing a synthesis of flyting and its Early Modern English descendants with comparable African verbal-combat games such as Ikocha Nkocha."
Maybe it developed independently in various societies as a ritualized way of fighting without violence. Now it's becoming a Twitter form! 
I was going to google.
Oh I did anyway..
Dozens is oral legacy rooted in survival
The dozens is a game of verbal combat, played mostly by black males on street corners. It is designed to teach participants to maintain control and keep cool under adverse circumstances.
"We played the dozens for recreation, like white folks play Scrabble," H. Rap Brown once said.
http://articles.baltimoresun.com/1994-02-11/features/1994042244_1_mothers-dirty-dozens-censures
The dozens is a game of verbal combat, played mostly by black males on street corners. It is designed to teach participants to maintain control and keep cool under adverse circumstances.
"We played the dozens for recreation, like white folks play Scrabble," H. Rap Brown once said.
http://articles.baltimoresun.com/1994-02-11/features/1994042244_1_mothers-dirty-dozens-censures
I assume the reason I know what "playing the dozens" means is due to the fact that I'm an obsessive reader - books, magazine articles, newspapers, cereal boxes, movie reviews...
Somewhere along the line, I came across the term - loved it and remembered it. 
The Dozens is a game of spoken words between two contestants, common in black communities of the United States, where participants insult each other until one gives up. It is customary for the Dozens to be played in front of an audience of bystanders, who encourage the participants to reply with more egregious insults to heighten the tension and, consequently, to be more interesting to watch. It is also known as "blazing", "hiking", "roasting", "capping", "clowning", "ranking", "ragging", "rekking", "crumming", "sounding", "checkin", "joning", "woofing", "wolfing", "sigging", or "signifying",[1][2] while the insults themselves are known as "snaps".[3][4]
Comments in the game focus on the opposite player's intelligence, appearance, competency, social status, financial situation, and disparaging remarks about the other player's family members—mothers in particular ("yo? mama..."
—are common. Those outside the African-American community, in fact, often use the incorrectly specific term "yo momma jokes" to refer to the dozens. Commentary is often related to sexual issues, where the game is then referred to as the "Dirty Dozens".[5]
