A dydoe is a piercing done through the ridged edge (known as the coronal ridge) of the glans. Urban legend holds that it was originally devised by circumcised men to regain some of the sensation that circumcision had taken away from them. That said, uncircumcised men can get dydoes only if they have quite loose foreskins — a tight foreskin can put damaging pressure on healing piercings.
This piercing is one of the more painful male genital piercings, and without proper jewelry and aftercare dydoes are prone to rejection. Some males do not have the anatomy to be able to successfully hold this piercing. Generally, a coronal ridge of about 6-8mm or more is best suited to hold this piercing, though some people have had success with a coronal ridge only as high as 3-4mm.