The Yakuza are obviously deeply rooted to tradition and honor, much like the traditional samurai of the olden days. Full body tattooing and to a greater extent the loss of a pinky finger, both very painful procedures, are acts performed in order to show ones devotion to the "clan", similar to the way seppuku was performed by samurai.

But some Yakuza sew pearls into their penis. This sounds much more painful than shoving a sword into you stomach.

A Yakuza, if sent to jail, will sew a pearl into his penis for two main reasons:

  1. Loyalty – obviously if a Yakuza is in jail they probably did something illegal that was part of the lifestyle they’re coming from. Inserting a pearl, at the rate of one per year, shows that the Yakuza is not forgetting about where he comes from, and that he will remain loyal to his clan even through bars.
  2. His Woman – the second reason a Yakuza will add a foreign object into his penis is for his woman. With the pearls in his penis he can make up for years of lost time; the pearls will act as added stimulation during intercourse, giving the woman much more pleasure.

Now that you (as a Yakuza) have decided why you're sewing pearls into your penis it's time to get down to the real business of it, which will take an incredible amount of courage. Because you are in prison the means by which you can sew a pearl into your penis are limited. So basically you're going to have to do it with a sharpened chopstick and a fake or real pearl, it doesn't really matter which.

With your flaccid penis carefully cut into the skin, on the underside just below the head, and then carefully insert the pearl. Now, if you are lucky enough to have obtained thread and a needle, sew the wound shut, if do not have these items necessary to sew with then just bandage it up and hope for the best.