i ate a small male last weekend and he had his GUNS LOADED. watch out ladies
i would think that by spitting up stomach content when feeling threatened by either another predator fish, or a jig in the lip, the predator fish may eat or be distracted by the fish/stomach content it spits out allowing it to swim away.
which i guess is why they always have their mouth open on the way up and outa water. and if their mouth is open, that explains why walleye rarely cut through 6-10lb test line. my guess.