Number 4: I know you heard this before
"Never get high on your own supply"

from The Notorious B.I.G. – Ten Crack Commandments Lyrics on Rap Genius

Meaning

Frank Lopez tells this to Tony Montana, advice famously ignored.

Also a reference to the famous Ice Cube line from the N.W.A. song “Dopeman”

This is actually rule number two:

Frank Lopez: Lesson number one: Don’t underestimate the other guy’s greed!
Elvira Hancock: Lesson number two: Don’t get high on your own supply.

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