Tattoos for witnessing

In light of the insistence of so many of my students arguing that tattoos are a witness for the Gospel, here's a reminder that the primary witness is in the living out of our relationship with Christ...My understanding of Scripture is that this is an issue of wisdom rather than a black & white, always right or always wrong kind of issue (see Romans 14 for more on that...), however, I do think its important to remember that our witness is much more than a stamped tee-shirt or bumper-sticker or tattoo.