This message is probably not for the squeamish! If the idea makes you go "ew, shudder, OMG, yuck" please just move on.
Just got into this with a friend of mine. Actually, I knew I'd like it -- before I even knew what BDSM was, as a teenager, I'd sometimes feel compelled to pierce what little foreskin I have with safety pins in an attempt at what I later learned was called "infibulation." (Yes, I've also got an enforced chastity fetish). This was a very formative erotic experience.
Anyhow, I've only recently gotten up the nerve to start exploring this again, and with someone else. Using completely STERILE and surgical-grade-steel hollow-tipped needles (the kind a professional piercer would use), my friend actually pierced the head of my cock. Not all the way from one side to the other, but more like through the edge of the corona. It's one of the hottest things I've ever experienced, and I'd fantasized about it for years, but had been afraid to try it. Eventually, there were about five needles through the head of my cock, all pointing upward -- it looked very crown-of-thorns-ish.
Toward the end of the session, my friend had me jack off (carefully and agonizingly slowly -- I didn't want to accidentally prick hand or jostle the needles too much) to orgasm and, as I was cumming, my friend pulled one of the needles out. Needles to say, there was blood everywhere, as if I'd just cum blood instead of semen. This totally shocked me and frightened me a bit, but it was also such an intense rush and, in retrospect, a strangely beautiful experience, erotic on a kind of primordial level.
And just in case anyone's still worried about safety, this person is a professional piercer (and long-time friend), knows all about the proper hygienic procedures, used sterile gloves, put the needles in a proper sharps container, etc. I wouldn't have done this if I hadn't known and trusted the piercer really well.
Anyhow, just thought I'd share my experience and also see if anyone else out there has had a similar experience.