And my heroin is on metaphors
This is a response to Kendrick saying his music gets people higher than cocaine. Kendrick says people get high off his songs but Lupe goes one up and says even drugs are getting high off his songs.
Lupe is suggesting in the next part of the line that the drug to his metaphors is his brains, and his metaphors are drugs to his heroin (could just be playful talk about his addiction to metaphors).
Notice that he reverses order of the metaphor (his metaphors should be on heroin) shortly after mentioning antonyms. Too clever!
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