I, cis white guy in the bay, was hired as a consultant to help build out a product and was pair programming with a woman founder & new engineer and made some passing comment about the CSS quality not being "ideal" or something of the sort. This was later brought up as something that they interpreted as some kind of sexism which completely caught me off guard and put me in a very awkward position of having to respond to that and explain that it was just poorly phrased, not sexism.
In the grand scheme this was very minor situation, e.g. no managers, HR, or social media involved, just between a few people on the project, but it's something I'll never forget and had colored how I interact with women going forward.
Basically I just want to avoid that ever happening again because if you're on the "No I'm not sexist" side of the argument, you've basically already lost in how society engages these days.