(I do not have any ideas for how to get free tattoos. I do, however, have free ideas about things that would make good tattoos.)
1. Measuring tape. This is a risky one because skin stretches over time and so you might eventually end up with an inch that is not actually an inch long. But as a knitter I feel like the benefits (primarily AWESOMENESS and the ability to measure stuff) outweigh the risk. Though I guess you should be sure to get it on a spot that is less likely to get fatter or more muscle-y.
2. For sock knitters: toe decrease marker. If you knit your socks top-down, get a tattoo on your foot where you need to start your toe decreases. (I did not come up with this idea. I read it on a knitting blog. Probably Yarn Harlot, but I don’t remember for sure.)
3. Toe knuckle tattoos. I would love to get knuckle tattoos, but I can’t think of any four-letter words that I want on me forever–at least not in such a visible place. So what about getting them on your toes?
4. Stocking seams. This is my favorite. Probably because it is the best tattoo idea of all time. I mean, if you are a lady of a vintage-y persuasion. I would totally get this if I did not already have a tattoo planned for each of my calves. Hell, I might get this instead, because it is the best tattoo idea of all time.