I don't have a lip tattoo (yet). Actually, I don't have any tattoos. However, I've been thinking about getting a lip tattoo for some time now. Admittedly, my situation might be a little bit different than that for other people in ponyplay. Part of the reason for wanting the tattoo is ponyplay related (lip tattoos are often used by bio-horse registries), but the main reason I have been considering getting one is for other, more personal reasons which I won't get into here.
I guess I was wondering if there are other ponies who get lip tattoos as part of the whole ponyplay experience, or perhaps more generally as part of the BDSM lifestyle (part of being owned perhaps). I actually don't know of any ponies with lip tattoos, so this may be further out there than most involved in ponyplay will go for the fetish. Indeed, I wouldn't be considering one based on ponyplay alone.
In a way, I think lip tattoos are strangely personal because of the fact that they aren't visible. Even if you are completely naked they can't be seen. Nobody really thinks to check the insides of the lips. Most trainers, owners, grooms, etc. won't notice them when putting on the bridle and bit. Unless you actually tell somebody it seems really unlikely that they would ever know about it even if you are otherwise intimate with the person.
So, this has really made me start to wonder how common they really are and what they mean to people. There isn't that much space on the insides of the lips so you have be pretty selective about what goes in there. While I do know exactly what I want to written on my upper lip, I have to wonder how many others there are out there who get a lip tatttoo for the same reasons.