Right now it's appparently very popular to get a piercing or tattoo. Whatever your PERSONAL reasons are for doing so, it will be seen by some or many that you bump into as your acquiescence to the current trend. The PERSONAL reasons may be "going along with the trend" -- in other words, you might actually be getting a tattoo or piercing in order to be trendy (although probably nobody really uses that word to describe himself). But then again maybe not. Perhaps you are getting a tattoo for some other reason -- your SO finds them sexy and it's an act of love on your part, for example (there are probably tons of other reasons but this one just came to mind; roll your own here and please don't flog me for not thinking up a good example!). But personal reasons aren't apparent to the vast public who will see the pierced eyebrow, for example. They will just see another pierced eyebrow, and think of the "trend" and think that you are just another part of same.
Does this make it clearer?
Again let me say I am not trying to say that getting a piercing or tattoo is "wrong" -- or that the trend should be shut down or reversed or ANYTHING of the sort. In this post I am just trying to distinguish between the "statement" that your actions make, and your actual reasons for making those actions, which could be quite different.