tuna bum Share definition Flag A bum hole that stinks of fish, can be called tuna butt or bum hole as well. Person 1- Just had a poo, wiped my ass, stinks like fish! Person 2- Errrr tuna bum. tuna bum by Pip-squeak January 4, 2021 0 0 Get merch Get the tuna bum mug. Buy Now — $32.95 See more merch