A thrase/pun used by splatoon players to replace "on god"
Other splatoon-related puns include(to my knowledge):
Krill yourself
for eel!
cod fucking dammit
I swear to cod-
Less common:
the shell?
holy karb
Splatoon player 1: The body is dispensable the grind is not
Splatoon player 2: on cod!