I gotta say, this video was exactly what I was looking for. My son sent this to the Family group chat this morning (when he definitely wasn't supposed to be having his phone during school), and after watching it, I immediately subscribed. Not only does Dr. Taylor W Jones use the seal script for the Chinese word "wen" (culture, literature) as his YouTube channel icon, he has a PhD in linguistics and wrote his thesis on regional variation and AAVS (African American Vowel Shift) in African American English (Labov was in his dissertation committee). Sold.

His analysis here is both academic enough and also, since he happens to be in Pennsylvania (he got his PhD from UPenn), he has the Philly chops to break down Skrilla's lyrics. Some of my notes:

"What happens when people don't understand what a Black American is saying is, they just make shit up for it to mean. They go by context clues, but they usually don't have all the context."

He talks about "criminal cant" — ie, jargon intentionally produced to obscure illicit activity.

He references "Shibboleth" which I had forgotten was a linguistic test by the Gileadites to weed out Ephraimites, who would have pronounced the word as "sibboleth." Sidenote:

David Marcus has contended that linguistic scholars have missed the point of the biblical anecdote: The purpose of the later Judean narrator was not to record some phonetic detail, but to satirise the incompetence of "the high and mighty northern Ephraimites". "The shibboleth episode ridicules the Ephraimites who are portrayed as incompetent nincompoops who cannot even repeat a test-word spoken by the Gileadite guards".

(from https://www.journals.uchicago.edu/doi/10.1086/MAR199208108)

SideSidenote: You know how some Spanish speakers have deliberate lisps and how that was attributed to a Spanish king who had a lisp and so it was adopted by Spanish speakers because, you know, "prestige"? Well that urban myth has been debunked by scholars.

Anyways, I'm sure someone has done a dissertation on how much and how often slang terms like "6-7" and "sigma" come from misunderstandings or misinterpretations or just an overwhelming desire to want to be cool by adopting terms that signal you're "in" and "hip" without actually understanding how they were originally used. "Bruh" is today's "dude" which, incidentally, was a Victorian variant of "dud" as in "fashionable clothing" or "drip" in today's vernacular. There's always some "inside/outside" "cool/uncool" line being drawn in all of this slang.