I think I might get a similar tattoo, but with a URL, QR code, and a chip. The url and QR code will point to a github repo with my DNR. Which I will sign with a "No really, I mean it" statement that is cryptographically signed, maybe once a day, once a week, something like that. The chip will also have the key to authenticate the git signatures. And, in the DNR, I will have directions to contact my pre-paid attorney, with further direction to summon them to the ICU and make sure my wishes are carried out.