Having a zero-tolerance policy for sexist, racist, etc. comments can be a big thing. A recent blog post talked about how people were posting really hateful, ins

Having a zero-tolerance policy for sexist, racist, etc. comments can be a big thing. A recent blog post talked about how people were posting really hateful, insensitive stuff on Facebook about a talk during the talk. Make it clear that comments of that sort won't be tolerated, and make it clear to attendees that if it does happen and is reported, it will be dealt with effectively.