I cut my teeth on the blacktop, I'm used to something cruel
Blacktop = Asphalt
Cut my teeth = to grow up and mature (figuratively).
He matured and learnt the realities of life on the blacktop of a playground(presumably), where he was bullied by other kids. It was this playground where he got used to cruelness.
Again, he alludes to his lack of hood-ness: he was raised on a school blacktop with quarrelsome kids.
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