Don't let me fill my clip up in ya back and headpiece

from The Notorious B.I.G. – Gimme The Loot Lyrics on Rap Genius

Meaning

“Don’t do anything that would make me unload my Tec into your back and head” (ie trying to flee, not giving Biggie the loot, etc.)

Interestingly since Biggie threatens to shoot them in the back, for this robbery he must have approached the guy from behind. Attention to small details like this one really differentiate The Notorious B.I.G. from the average rapper.

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