pre dinner mayo Share definition Flag the act of eating a large spoonful of mayonnaise while dinner is still cooking it's good for you GRAB THE MAYO FOR A PRE DINNER SNACK! (eats the pre dinner mayo then whispers) it's good for you! pre dinner mayo by UM North Quad September 20, 2011 0 0 Get merch Get the pre dinner mayo mug. Buy Now — $32.95 See more merch