Penile subincision is a form of body modification consisting of a urethrotomy, in which the underside of the penis is incised and the urethra slit open lengthwise, from the urethral opening (meatus) toward the base. The slit can be of varying lengths.
Subincision is traditionally performed around the world, notably in Australia, but also in Africa, South America and the Polynesian and Melanesian cultures of the Pacific, often as a coming of age ritual. The practice has been taken up in the western world in recent years for the purpose of sexual pleasure or aesthetics.
Disadvantages include the risk of surgery, which is often self-performed, and increased susceptibility to sexually transmitted infections (STIs). The ability to impregnate (specifically, getting sperm into the vagina) may also be decreased.
Subincisions can greatly affect urination and often require the subincised male to sit or squat while urinating. The scrotum can be pulled up against the open urethra to quasi-complete the tube and allow "normal" urination, while a few subincised men carry a tube with which they can aim.
Read more about Penile Subincision: Cultural Traditions, Related Modifications