This isn't true for everyone, of course, but once we get older, many of us put aside some things that are frivolous and start to get practical.
So get a tattoo while you still have the desire to do so. When you're 50 and worried about how much beef goes for at the grocery store, it'll remind you that there are more beautiful things in life waiting for your attention. Whether that's a piece of art on the sleeve of your arm or a poem that's reached in and touched something deep inside you, follow your whim and trap that beauty on your body.