A 70-year-old Australian man came into the emergency room with a bleeding penis after "self-insertion of a fork into the urethra to achieve sexual gratification," according to a scholarly article published in the International Journal of Surgery.
The metal fork was apparently hard to pull out, but success was finally "achieved via forceps traction and copious lubrication." The emphasis on "copious" is my own.
Although doctors cannot fully comprehend why some people feel the urge to put things up their penis, it still happens fairly often. Even in the world of penis insertion, however, forks are particularly "rare." According to the article, doctors are more accustomed to dealing with people putting these items up their urethra:
needles, pencils, ball point pens, pen lids, garden wire, copper wire, speaker wire, safety pins, Allen keys, wire-like objects (telephone cables, rubber tubes, feeding tubes, straws, string), toothbrushes, household batteries, light bulbs, marbles, cotton tip swabs, plastic cups, thermometers, plants and vegetables (carrot, cucumber, beans, hay, bamboo sticks, grass leaves), parts of animals (leeches, squirrel tail, snakes, bones), toys, pieces of latex gloves, blue tack, tampons, pessaries, powders (cocaine), fluids (glue, hot wax).
You can read the full article below, but WARNING, there are some incredibly graphic pictures toward the end, which include nudity. These are not for the weak of heart or stomach.