In Minecraft there are these squidward like villagers called Testificates. In a recent update they were given new abilities such as having babies to repopulating a town based on the number of houses there are. Since the requirement for a "house" is simply a room with a roof and a door, I decided to spend my time building a massive city for the Testificates to populate, using a generated village as a starting point.
After building a number of houses, I began noticing the little children running wild and there becoming quite a LOT of villagers. I undertook a huge task of building a BIG open area underground with a couple doors and lights. Because the area was so big, the Testificates began to... um... OVER populate.
These little buggers reproduced the village so fast that I couldn't keep up and soon they were overflowing out of buildings. Mob attacks couldn't keep up with the rate they were repopulating, and the iron golems that kept spawning (for every 15 villager a new one spawns) made sure mobs weren't an issue.
I tried burning some of the houses down with the Testificates inside, but it didn't help. They were repopulating out of control at this point. My poor village was being overrun by these weird squidward like creatures. What was I to do???
In the end, the answer lied with figuring out their programing. They respond to doors and enclosed spaces and will attempt to go through a door if there is one nearby, especially at night. Knowing this I went around the village and removed every door except one. Inside this lone house I removed the ceiling and poured a lava trap. Come nightfall, all the Testificates would try to enter through the one door in town and consequently meet their demise. It was a sad day... but I did what needed to be done. I've estimated that at one time I had around 250 Testificates running around trying to get inside buildings. Horny little buggers...
I don't use mods or cheats, so this whole epidemic could actually happen to you too. When building houses for Testificate villagers... be careful. Too many houses, or too big of an open space, could result in a Testificate infestation of epic proportions... and your only way out will be to commit virtual genocide.