No sir! Definition 1 of 3Pro Tip 1/3Emphatic Refusal Stresses a strong denial, showing you are very certain about saying no. Will you ever quit your job to follow him? No sir! Pro Tip 2/3Not Polite Despite the word 'sir', it's informal and can be impolite or abrupt in serious contexts. Return the borrowed money? No sir! Pro Tip 3/3Emotional Weight Often carries a tone of frustration or strong emotion. Should we just give up now? No sir! We keep going.