One of the most difficult parts of living an anti-racist existance is confronting racism when you heard it. Especially when you heard something said by someone you love or respect.
There is no one "right" way to respond to racists comments you hear, but there is a wrong way: not responding at all.
Click on each commonly overheard racist comment for one suggestion as to how to respond.1 As with all pieces of your journey to anti-racism, the more you practice, the easier it will become.
Try saying this:
When in doubt, ask the question:
When you say "they", who are you talking about?
This questions forces people to examine what they said and most will realize their unintended impact when they try to answer.