Sorry, dozed off a bit.
That's pretty cool Attimus. Something I remember from college (back in the dark ages) was the skin of the back has a very low density of nerve endings, so pain sensation is much less. You have to have quite a distance between 2 pin points touching your back to be able to detect that are actually 2 touching you at the same time. Mostly it just feels like one point. That would be enough pain for me to skip the tattoo thing!
And with that scintillating tidbit of useless information, I will sign off. Goodnight!