Acronym. Stands for Male Answer Syndrome. (Pronounced - MASS) Used to describe a male know-it-all who doesn't really know-it-all. Not necessarily a complete idiot, but someone who tends to dish out inaccurate information on a regular basis - but with complete confidence and a touch of arrogance. Usually provides this information without invitation or provocation. A Cliff Clavin if you will.
Sandy and I were discussing the new guidelines, and John -in typical MAS fashion, chimed-in with his unsolicited anecdotes.