The tipping customs in the U.S. are a bizarre mess of unspoken rules that are explained via doublespeak if they're explained at all. You tip restaurant waitstaff, but not shoe store clerks. Taxi drivers but not bus drivers. Hairdressers but not dental hygienists. Belly dancers but not ballet dancers.
And then, today, I learned that while you don't tip chiropractors, you do tip massage therapists.
The massage itself was good (my first one!). It showed me a large number of spots on my body where my muscles are sore all the time, except I'm so used to it that I don't notice. And there are weird connections everywhere - sometimes she would be working on one area, and a whole separate area would be twinging like mad, and I would get all tensed up in response. She was good about explaining some of why that is. So although I wouldn't say it was a relaxing experience, it was definitely enlightening.
Anyway, it didn't even occur to me that tipping might be expected until the end of the session when I was at the counter paying. As a result, I'd only brought enough cash to cover the cost they'd told me in advance. Without thinking about it, I asked them directly if I was supposed to tip, and the reply was: "Oh no, you don't have to do that. It's not mandatory or anything."
For those unfamiliar with tipping doublespeak, that means: "yes."
So naturally after I'd asked that without thinking, I also didn't tip because I didn't have the funds. Which means I suck as a person for being insulting and she probably hates me now. :(