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It says one hundred percent guaranteed, you moron!
— Businessman ‧ Fast Times at Ridgemont High

Behind the line May contain spoilers.
Our reading
An editorial interpretation.
The speaker insists that an absolute guarantee should settle the matter. Emphasising the full hundred percent makes the promise sound beyond dispute, while the insult turns that insistence into an outburst. The line conveys impatience with anyone who questions the wording.
Context reviewed