ROTFLMBFAO Share definition Flag 'Rolling On The Floor Laughing My Big Fat Ass Off'. Used in coffee-rooms when something is TRULY a laugh-it-up riot. ROTFLMBFAO!!!!!! Stopit,stopit,yur gunna make choke!! ROTFLMBFAO by Victor Van Styn August 21, 2005 0 0 Get merch Get the ROTFLMBFAO mug. Buy Now — $32.95 See more merch