Miss Manners. One of my favorite columns involved how to respond to a racist or sexist or other offensive joke offered in a polite gathering. Miss Manners recommends silence and puzzlement. As in "I'm waiting for the joke." As in "It's not my job to get you out of this."
It doesn't require outrage, or explanation. It requires not going along to get along and not taking the other person off the hook.
I was reminded recently of how often I am called on to review a manuscript, or pass on information, or answer an interview question where I have to take that stance. You will never see mention of my name in these articles or acknowledgement in the book. You will not hear me quoted or see a link. But my voice DOES have power anyway when I refuse to go along with the joke, or the message, or the opportunity even to promote my own work. Not uncommonly the times I seem silent are the times of my proudest advocacy.
You may see it without knowing when a researcher changes the text on a study because someone like me says it is phrased in a way that is off-base. You may see it in a book that is very different than the manuscript. I'm proud of the way articles have been reframed to avoid sticky issues that I pointed out, even at the cost of not getting my name or organization in the credits. You may even see it in the people who avoid me like the plague for having made them uncomfortable.
Some of advocacy has to do with what we WON'T say, and won't get quoted for. It's still important, and it's worth it. Use your voice, and your silence: it works!