1) If you're ever trying to explain something and can't, or just don't know how to start, put on a very long-suffering look and say "You wouldn't understand. It's postmodern."
2) If you ever do successfully explain something and someone says they don't understand, say, "Of course you don't. It's postmodern."
3) If a postmodernist happens to be among the listeners, switch gears and claim they wouldn't understand because they're just too postmodern.
4) If you have nothing at all to contribute, look mysterious and broodingly pensive.