There are people who are, for whatever reason, poking and prodding their bodies with needles and wires, and almost any pieces of metal they find irresistibly attractive. This is the way they express themselves (however, psychologists are often talking about tattoos and piercings being the kind of self-injury and self-mutilation).
So it was just a matter of time when the piercing lovers will transfer their passion over to their speechless and never arguing companions. Have you ever seen the car with piercing? If not yet, I bet you will see one of those pierced vehicle riding around your neighborhood, with even more abundantly pierced driver inside.