The Kinsey Institute site
Always fascinating, on the sexual practices of Papua New Guinea:
The Dobo, who live on a small island off the coast of the main island, live in constant fear of sorcery from their wives. Because they believe that they are particularly vulnerable during intercourse, Dobo men have to continually weigh their need for sexual gratification against the possibility of sorcery when they try to satisfy their sexual need (Davenport 1997, 126).
Much of it makes for disturbing reading. Papua New Guinea is a terrible place.