After mentioning that two current movies (see recent posts) would be good for cross-cultural discussions, I reminded myself that not everyone would approach these matters in a productive way. Sometimes these conversations "just happen" and given the relative skill level of each person in the conversation the experience can range from crappy to lifechanging. A random method is not one I would recommend.
Why? Ongoing relationships and the building of mutual good will sufficient to continue a discussion over time sometimes suffer when people talk without sharing a culture of what is "too far" or provocative. Especially if someone hurt during the conversation has no means of asking for a change in the rules or norms and also may be viewed as vulnerable or weak relative to the other discussants (who stay a bit one-up due to not revealing any vulnerability).