CentralNotice From Wikipedia, the free encyclopedia Jump to: navigation , search For the human sexual behavior, see Frot . Two individuals of Pseudobiceros bedfordi preparing for penis fencing. P. bedfordi is exceptional in that it applies sperm onto the partner's skin rather than injecting it. Penis fencing is a mating behavior engaged in by certain species of flatworm , such as Pseudobiceros hancockanus . Species which engage in the practice are hermaphroditic ; each individual has both egg-producing ovaries and sperm-producing testes . [ 1 ] The flatworms " fence " using two-headed dagger -like penises which are pointed, and white in color. The mating ritual involves a violent battle during which two hermaphroditic flatworms attempt to pierce the skin of one another with one of their penises. One organism will inseminate the other; this flatworm becomes the f...