Negative Bume Share definition Flag When one's bottom is so flat it curves inwards instead of outwards. 'Ew. Look over there, that boy has a negative bume. Hit the gym once in a while! Maybe try some Bero and lobster mac and cheese! Start the bulk mate!' Negative Bume by BigBeroAirConditionerNumber1 March 14, 2025 Get the Negative Bume mug.