The koteka, horim, or penis gourd is a penis sheath traditionally worn by native male inhabitants of some (mainly highland) ethnic groups in New Guinea to cover their genitals. They are normally made from a dried-out gourd, Lagenaria siceraria, although other species, such as Nepenthes mirabilis, are also used. They are held in place by a small loop of fiber attached to the base of the koteka and placed around the scrotum. There is a secondary loop placed around the chest or abdomen and attached to the main body of the koteka. Men choose kotekas similar to ones worn by other men in their cultural group. For example, Yali men favour a long, thin koteka, which helps hold up the multiple rattan hoops worn around their waist. Men from Tiom wear a double gourd, held up with a strip of cloth, and use the space between the two gourds for carrying small items such as money and tobacco.
It is traditional clothing in certain New Guinea highlands societies including in the Grand Baliem Valley of Western New Guinea and the Ok Tedi and Telefomin regions of Papua New Guinea. It is worn without other clothing, tied in upward position. The use of penis gourds has also been documented for tropical Africa and northern South America.
Many tribes can be identified by the way they wear their koteka. Some wear them pointed straight out, straight up, at an angle, or in other directions. The diameter of the koteka can also be a clue. Contrary to popular belief, there is little correlation between the size or length of the koteka and the social status of the wearer. Kotekas of different sizes serve different purposes: very short kotekas are worn when working and longer and more elaborate kotekas are worn on festive occasions. The koteka is made of a specially grown gourd. Stone weights are tied to the bottom of the gourd to stretch it out as it grows. Curves can be made in it by the use of string to restrain its growth in whatever direction the grower wishes. They can be quite elaborately shaped in this manner. When harvested, the gourd is emptied and dried. It is sometimes waxed with beeswax or native resins. It can be painted, or have shells, feathers and other decorations attached to it.