Everyone assumes that using the language of other cultures is respectful, whether it's spoken language or nonverbal language. It can be - but sometimes it isn't.
Some background: I have multiple chronic health conditions, which can limit my activities. I have to carefully manage what I commit to, because I simply can't do everything. The problem of explaining this to people who aren't in my situation is summed up by Christine Miserandino in her essay The Spoon Theory, which is considered a standard citation by many people with disabilities. I've used it myself.
And then this morning, this popped up in my Facebook feed. Patrick Rothfuss is in general a good person, but this post is very definitely problematic. It uses the language I have to use as a person with disabilities, and repurposes it to say, in effect, "I don't want to deal with that particular bullshit source". The repurposing cheapens the language, making it harder for me to properly convey what I am dealing with on a daily basis.
But appropriation doesn't have to have practical effects the way this does to be problematic. Any use of language belonging to a group that you are not part of is appropriation, and it hurts. I'm not saying that you need to never say anything - but if someone calls you out on it, be apologetic, be remorseful, and ask what you should have said. Make it clear that it was unintentional.
Because it was, right? You weren't trying to be an asshole.