Harrison Ford would like to welcome you to Battle School! And then he'd like to depress you by reminding you of the ever-present alien threat and how you kids are the only thing standing in the way of another slaughter of countless innocent human beings. No pressure, though!
So Mazer Rackham pulled the ol' "Randy Quaid in Independence Day" maneuver, huh? Hey, it may not be original, but if it works, it works.