A Tribe Called Red Puns

In class we were talking about different ceremonies about "becoming a man". The story goes that a tribe in Peru sends nine 15 year olds into the woods for three days and each has to collect a different item. After the time is up the tribe beats drums to call the boys back. When they return the shaman lays them in a circle around the fire heads pointing inwards and begins to heat up a spear. After The metal is red hot they begin to cut out and remove the boys kidneys. Of course my class asked "why?!" Mind you we are taking this story as notes. He looks at as dead in the face and says "The culture believes they will receive their adultneys" Tl;Dr cuts out children's kidneys because they think they will grow adultneys.