Would a tattoo saying in Thai "Nothing is mine, not even myself" be considered offensive?

If it's on a sign hanging in a temple, you can be pretty sure the content of the quote is not offensive, and neither is there any particular taboo about tattooing yourself with Thai characters.

That said, visible tattoos on women are quite literally considered "tramp stamps" in Thailand, they're virtually unknown outside prostitution. And it's just generally a bad idea to get tattooed in a language you (& your tattooist) don't read & write fluently, all it takes is a small typo to turn it into gibberish or worse.

This phrase is safe to tattoo. And it's not offensive nor a "tramp stamp" for a foreigner as some comments stated. In Thai ????????? [thua rao eng] means both "ourselves" and also points towards the speaker/writer, thus the meaning "myself". I'm a native speaker of Thai, and I can assure you that we're not offended by this phrase. I don't know where other people get their negative views, but they aren't native Thai opinions. Just don't tattoo it on taboo spots, which is obvious.