Since when can "posse" refer to just one guy? 

When I hear the word "posse", I always think of old westerns, but I don't remember any of them where the hero was like "Let's get a posse together," and then just proceeded to change his clothes and talk in different voices to fight the bad guys.  That's a different movie entirely.  It's called The Nutty Professor II: The Klumps, and it's lame.