Although it's crept into America as well, all the stuff about El Chupacabra started in Honduras, I think. Large conspiracy about genetic mutations and being tested on local livestock for... profit? or something, there never really is a why. Don't believe it but it sure makes for some good scary stories. Started babysitting my cousin's kids and chupacabra is a recurring character in their late-night scary stories (that they ask for, they love them)
The best conspiracy theory is an international one- where all the elite people around the world are all a secret race of lizard people from the center of the earth. Kind of like 'They Live' but something about said lizard people trying to reclaim or rape the world of resources after escaping miles underground when their own surface-civilization collapsed. That or they were driven there. Either way, its hilarious to see and hear the people that actually believe it, write books about it etc etc