bumbiscuit Share definition Flag A humourous euphamism for faeces. Also can be used as a childish insult to siblings or friends. 1)'What took you so long?' 'I was making bumbiscuits.' 2) Shut your face you bumbiscuit. bumbiscuit by flingthecow January 5, 2009 0 0 Get merch Get the bumbiscuit mug. Buy Now — $32.95 See more merch