Surgical removal of male foreskin, which is shown in the etymology of the word itself - circum - around, encircling; cise - cut. Although it's often, if not universally, recognized as a religious ritual and a talking point for identity politics, that somehow this procedure gives you a unique identity, or this is a unique custom for Jews and Muslims, it's a beneficial measure for personal hygiene and STD prevention, and for some, a cosmetic work for a prettier, more magnonimous manhood.