The anus of a fish which, given that fish spend all their lives in water, would have to provide a very tight seal. Metaphorically, the term is usually used in conjunction with the words "tighter than a" to indicate that someone could hardly be more frugal with his spending.
Tom: "I never leave a tip when I eat out- even if the service was excellent".
Jerry: "Man, you are tighter than a fish's asshole".
Jerry: "Man, you are tighter than a fish's asshole".
by poo hole December 21, 2012
you- hey, whats the closest thing to a fishs asshole?
friend- uh idk
you- a finn!
friend- haha
you- haha
friend- uh idk
you- a finn!
friend- haha
you- haha
by simoisgod February 3, 2021
by ilovefishasshole December 30, 2017