Lip Plates.

"In Africa, a lower lip plate is usually combined with the excision of the two lower front teeth, sometimes all four. Among the Sara people and Lobi a plate is also inserted into the upper lip. Other tribes, such as the Makonde, used to wear a plate in the upper lip only. In many older sources it is reported that the plate's size is a sign of social or economical importance in some tribes. However, because of natural mechanical attributes of human skin, it seems that the plate's size often just depends on the stage of stretching of the lip and the wishes of the wearer.
In South America, lip plates are nearly always made from light wood.
Among the Surma (own name Suri) and Mursi people of the lower Omo River valley in Ethiopia,[2] about 6 to 12 months before marriage the woman's lip is pierced by one of her kinswomen, usually at around the age of 15 to 18. The initial piercing is done as an incision of the lower lip of 1 to 2 cm length, and a simple wooden peg is inserted. After the wound has healed, which usually takes 2 or 3 weeks, the peg is replaced with a slightly bigger one. At a diameter of about 4 cm the first lip plate made of clay is inserted. Every woman crafts her plate by herself and takes pride in including some ornamentation. The final diameter ranges from about 8 cm to a maximum about 16 cm[3].
Many recent sources (Beckwith and Carter for example)[4] claim that, for Mursi and Surma women, the size of their lip plate indicates the number of cattle paid as the bride price. However anthropologist Turton, who has studied the Mursi for 30 years, denies this.[5]
These days, it appears that Mursi girls of age 13 to 18 decide for themselves whether to wear a lip plate or not. The lip plates worn by Mursi and Surma women have been instrumental in making them a popular tourist attraction in recent years, with mixed consequences for these tribes.[6][7]
In some Amazonian tribes, young men traditionally have their lips pierced when they enter the men's house and leave the world of women.[8][9] Lip plates there have important associations with oratory and singing, and the largest plates are worn by the greatest orators and war-chiefs, like the well-known environmental campaigner Raoni[10] of the Kayapo tribe.
In the Pacific Northwest of North America, among the Haida, Tsimshian, and Tlingit, lip plates used to symbolise social maturity by indicating a girl's eligibility to be a wife. The installation of a girl's first plate was celebrated with a sumptuous feast.[11]
Tribes that are known for their traditional lip plates include:
The Mursi and Surma (Suri) women of Ethiopia
The Suyá men of Brazil (most no longer wear plates)
The Sara women of Chad (ceased wearing plates in the 1920s)
The Makonde of Tanzania and Mozambique (ceased wearing plates several decades ago)
The Botocudo of coastal Brazil (in previous centuries, both sexes wore plates)
Aleut, Inuit and other indigenous peoples of northern Canada, Alaska and surrounding regions also wore large labrets and lip plates; these practices mostly had ceased by the twentieth century.
Some tribes (Zo'e in Brazil, Nuba in Sudan, Lobi in west Africa), wear stretched-lip ornaments that are plug- or rod-shaped rather than plate-shaped."

..taken from Wikipedia.