Yautja use trophies to show off their kill. They usually behead their kill and put them on a wall to show their kills. Humans and Xenomorphs are usually the chosen races for trophies. Trophies are usually claimed when Yautja killed a valuable or formidable targets (such as Xenomorphs, Humans, Engineers, Dinosaurs, etc.). If one warrior were to kill a fellow Yautja intentionally or not claiming their head as a trophy would be considered a crime to the Yautja Honor Code.