Her new prima donna I smelt it
Kendrick can tell just by her smell, possibly overly gaudy perfume, that she is a prima donna, someone who is vain, arrogant, or generally obsessed with material things.
There is also the pun on prima donna and pre-Madonna by which Kendrick means he sees/smells, that this woman will become famous one day, like Madonna, hence the pun on pre-Madonna and prima donna. Since Kendrick is the new westcoast rap king, he even wants to be her new pre 2Pac, whom Madonna had an affair with.
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