The chupacabra comment got me to thinking about this...
http://en.wikipedia.org/wiki/Popo_Bawa
Popo Bawa, also "popobawa", which means "bat wing" in swahili is a monster purported to live on the spice islands of Zanzibar. Its existence has not been documented. Variously described as either a ghost or ogre with a gigantic penis and bat wings. His presence is usually announced by the sound of scraping claws on their roof and a sharp, pungent smell. Different from other incubus legends, Popo Bawa only attacks men and only in their own beds, resulting in many men sleeping outside in streets or on porches after recent reported attacks. He attacks men as they sleep, overpowering them, holding their face to the floor and sodomizing them for up to an hour. Popo Bawa victims are mostly poorer residents on the island of Pemba, though other reports have also come from other islands and coastal Tanzania. The victims are threatened with repeated, and longer, sodomizations if they do not let their friends and neighbors know of their experience. It is thought the cause of the Popo Bawa appearing is the result of episodes of sleep paralysis.