Bum bum Share definition Flag A way to say thicc ass but with no profanity. The thicker it is the more bums u add. Prabh: Yoo! Aaliyah sent pics of Nathan’s bumbum! Aaliyah: Yeha he was hella thicc you could call it a bum bum bum!! Bum bum by Prabhs December 17, 2018 0 0 Get merch Get the Bum bum mug. Buy Now — $32.95 See more merch