I think that a barbell like this would be perfect, and certainly much safer than a ring. *Visions of claws grabbing ring and pulling* oooooooooowwwwwwwwwww


Or, if you want to instead pay homage to the feline who was certainly just trying to save you the $60-$90 it would have cost to get it professionally pierced, you could wear something like this:

...though wearing a pink kitty on your nipple may make some people have doubts regarding your masculinity