Inversion, a form of genital bisection that involves a combination of subincision and superincision while leaving the glans intact allows the wearer to wear cartoonish "donut" jewelry and even turn the penis inside out, possibly having penetrative sex with the inside (urethral) nerves on the outside.
This is an extremely rare modification (best known from The Incredible Til). Most men who have it move to it after a subinincision (rather than as a first step) by either cutting up through the top half, or cutting back from a shaft apadravya. It is an extremely invasive and potentially risky procedure. A number of men also use this as a stepping stone to full bisection, later deciding to split the head as well.