Drop palmolive in a nigga dope
Make it come back even harder than before

from Lil Wayne (Ft. Rick Ross) – John Lyrics on Rap Genius

Meaning

Palmolive is a brand that is known for making hand soap. He is mixing it with pure cocaïne to make a stronger variation of it for his fiends.
Just a drop of soap when making cocaine into crack will make it harder like a soap rock, thus making it less pure but the hard texture is liked better.

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