Convention Game Preamble

Question for GMs: What do you start with?  Before the game session even begins, I mean.  Do you preface your con games with any particular words of wisdom, special rules, expectations, hopes, encouragement, warnings, introductions, anecdotes, jokes, questions or questionnaires?

Question for players:  Is there anything that has stood out to you over the years (good, bad, or weird) that a GM has said or done before a con game actually started?

That's it.  Please comment with your answers below.  Thanks!

VS