A number of years ago, any ornamentation of the cock/balls in a locker room would have seemed odd, i guess. However, times have changed and now if I see someone with the word "fuck" tattoo'd on their face, it doesn't shock me. Growing up in the 1960's, something like that would have gotten you arrested.
Similarly with piercings. When I saw a movie called "Gimme Shelter" with the Rolling Stones in 1970, Keith Richards was sporting a shark's tooth earring and I thought "wow, how odd." Now, at least where i live in Northern California, male earrings are hardly unusual.
So it is with other piercings, nipples, cocks, etc..although unless you are in a locker room situation, a pierced cock would not be noticeable.
Yet if the pierced nipple or cock is perceived by society as acceptable or daring, just like tattoo's, why should something as innocuous as a cockring take anyone by surprise?
Mind you, if I did see a guy in my gym locker room wearing one, I would probably find it a bit more unusual than seeing a pierced cock (both would be rare, however) as illogical as that may seem, given what i just wrote...go figure