A male genital piercing lying along the underside of the penis. The piercing enters the urethra at one point, and exits it at another. Specific placement depends on the length of an individual man's member, as well as where he wants it. A curved barbell is usually used, though sometimes a ring may be worn.
Oftentimes the piercing is placed further towards the end of the penis. This is the case if the dolphin is created by piercing one hole and connecting it to an existing Prince Albert piercing, which many dolphin-pierced men have done. It's also possible to connect several dolphin piercings, though I haven't seen it done.
Accounts of those who have dolphins report that the piercing can bleed quite a bit. If the jewelry is not sized correctly, the healing process can be long and painful, but a properly fitting barbell should make healing easy. Basic care for a new dolphin is like any other piercing wash with a simple anti-bacterial soap twice a day; sea salt soak once a day; no band-aids and let it get some air every now and then. Urination also helps heal (as an individual's urine is sanitary to that individual before it leaves the body) as it helps wash the side of the piercing you can't reach. This means new piercees should refrain from drinking alcohol or coffee for several weeks or until the piercing is mostly healed. New piercees should refrain from any type of sexual activity (even masturbation) for at least four weeks.
Urinary tract infections are a concern, but are rare among those who take care of the piercing while it's healing.