Genital bisection in males involves the splitting of the penis (and occasionally the scrotum as well). This still allows for erection, though often the two halves curve into each other, making insertion more difficult.
Genital bisection is an extension of a subincision, which is an extension of a meatotomy. As the urethra is exposed, some pleasure can be derived, due to the great abundance of nerves. This is why those who undergo previous procedures may choose to take it further, though in some cases the bisection might be done all at once.
Variations include keeping the glans intact so that only the penile shaft is bisected.