Many people have a tattoo today, so it's become mainstream. It isn't considered a sign of rebellion or creativity as much anymore.
There isn't anything the Bible that says getting a tattoo is sinful, but what type you get is. Rebellious ones are considered sinful. Tattoos as outward adornment to call attention to oneself is sinful. The motivation for getting one could be sinful such as to fit in or to stand out. If there is a message sent by the tattoo, then it could be the wrong kind and sinful. I suppose a Christian has to be mindful when getting a tattoo. In the olde days it was a pagan practice, usually based on superstition, so it may have been forbidden, but times have changed.