kind sir
Used when someone helps you in a way that goes over what you would typically expact. 'Kind Sir' shows you acknowledge his act of kindness and you also call him sir as a sign of respect and acceptance to his act. (Females can use this term to address a male)
If Michael drops all of his books on the floor while walking down the hallway, and someone he does not know too well comes along and picks up the books with him when he could have easily walked on. You would say 'Oh thankyou kind sir!'
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