To express disbelief.
To show enthusiasm.

Pronounced without the A.
Ruby: Two pound chinese in Camden
Nora: Reeeeeahhhh Boy
Methela: Shut up you neek
Nora: I aint no neek fool.
Ruby: Reeeeahhhh Boy is dis a beef ting
Nora: Nahh blud why you rinsin my word for.
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