A Mitch Share definition Flag An asshole; That guy nobody enjoys being around. Commonly uses the phrase, "Shut up, fag." "He kept telling me to shut up, and that I was a fag.""What a Mitch." A Mitch by Brenda Murphy September 18, 2011 0 0 Get merch Get the A Mitch mug. Buy Now — $32.95 See more merch