I could bust your eight, I’m-a do one too,
Choose your own adventure:
An eight ball is an 1/8 oz of cocaine. “Busting a line” means snorting a line of cocaine. She means not only will she bust your eight [ball of cocaine], but she’s gonna do one too. (Because she has her own too.)
It’s common in rap battles that contestants get eight bars to prove themselves. AB is saying she’ll be glad to battle-rap you, and will bust your eight bars with her own.
Since the numeral 8 looks like a vertical pair of testicles, she’s claiming that she could make her opponent ‘bust a nut’, or orgasm, while she has one as well.
Alternately, she could just bust your balls, she’s so badass. Watch yo sack, playa.
To help improve the meaning of these lyrics, visit “212” by Azealia Banks Lyrics and leave a comment on the lyrics box