A person who uses proper English, proofreads papers for fun, and gernerally corrects everyone's improper grammar. This person feels very ashamed when he or she is caught making such errors and corrects himself/herself often. It should be noted that a Grammar Nazi simply wants to help others and does not correct others out of arrogance.
In journalism class, many preferred going to the Grammar Nazi for help over going to the teacher.
September 03, 2007