“I think this will be fun, lively, and all-around entertaining,” said David Letterman just before the cast of American Idiot performed “Holiday” on his show last night. No such luck, though. Unless you’re really into the dopey, mugging and over-acting that’s required of all Broadway actors, even those who look like they were styled by the manager of your local Hot Topic. And am I the only one who thinks they don’t even sing it very well? Or are they just being punk? God, it hurts. Ew, yuck, cringe, etc.