(N.B.: NO EDIT EDITION. Normally, there is much more prep involved in this endeavor. However, that takes forever, and I want to post more. SO! HERE WE GO.)
Goblins are not actually humanoids. Well, they are, but they aren’t really mammals, I guess. What I mean to say is, they don’t get it on and have babies pop out some amount of time later. They sprout, and grow.
This is good, on a meta level. Now you don’t have to imagine sweaty grubgoblins humping each other, stinking up the place and leaving greasy humpspots all over. Bonus points if you don’t imagine them doing it dangling from inflated pigskin dirigibles.
Yes I know dirigibles have a solid framework. Bones, guys, bones inside.
Anyway. Goblins come into the world when a goblin corpse is buried, as you do with the corpses of just about any other respectable creature. This is why you see goblins—otherwise nasty beasts—burying their dead. They’re not being respectful. They’re planting new goblins.
Some weeks later some nasty spiny shoots arise from the ground. They are sticky and smell and will poke the shit out of you. Then a blossom, big and watermelon-red and stank. Just underneath this blossom, just underneath the soil, is a fetal goblin. When the blossom wilts, the goblin will shake free of soil and be the slicey self-defeating teenage-stand-in miscreants we all love.
This, obviously, leaves a bit of a problem for trying to
genocide clear lands of goblins. The orcs or humans or elves or whoever tries to kill as many goblins as possible, but then have to leave them to rot where they lie. Some will still sprout—like an acorn tossed to the ground—but most won’t. But try burying the nasty stinking things, and you’re just investing effort into raising the next crop.
This is why there are so many damn goblins when nobody can put up with the damn things.