fag-muffin Share definition Flag just someone who happens to be an idiot; something to call someone when they do something stupid one of your friends comes up behind you and kicks your leg, you fall over and yell "fag-muffin" and inflict physical pain on him/her. fag-muffin by lesley martins April 21, 2010 0 0 Get merch Get the fag-muffin mug. Buy Now — $32.95 See more merch