I could see Dave pulling off the "one ear earring hoop" thing pretty well. Cronus probably could too, but claim he "did it first".

I've seen cool art of a lot of characters with piercings as well, such as this Dirk wearing some Pain (Naruto) levels of piercings.

I could also see that even underneath the skeletal body suit, Kurloz would have full body skeleton tattoos, and even plugs for his ears. I could see Gamzee with plugs as well, actually. Rufioh might have ear studs, and I could easily see him with a bull ring as well.