@foone My interpretation is that A) tattooing does not qualify as "Linking" under the GPL's definition, and B) even if it did, the person's body would qualify under the System Library exception. As such, there wouldn't be an issue, provided the tattoo artist gave the recipient a copy of the GPL and the Corresponding Source for the artwork (or a written offer to receive the Corresponding Source through some other means, for free or for a fee no greater than their cost to perform this service).