The MAC-11'll clap your melon and give your ass spaghetti face

from Royce Da 5'9" (Ft. Travis Barker) – Legendary Lyrics on Rap Genius

Meaning

He’ll shoot (“clap”) you with his MAC-11 machine pistol in the face until it’s so torn up it literally looks like spaghetti.
Also note the wordplay of using MAC (as in macaroni) and spaghetti — two types of pasta.

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