Disclaimer: This has nothing to do with mustaches.
I was listening to NPR this morning and heard a piece on the new book, As They See 'Em: A Fan's Travels In The Land Of Umpires by New York Times reporter Bruce Weber. Interesting stuff. Weber was an umpire for a while himself, and discusses things ranging from how umpires develop different styles of calling "strike," "out," etc. (they practice in front of a mirror), and what goes on during on-field arguments (lots of fun stuff). He also spends some time describing umpire college, which I imagine to be something like the Police Academy movies.
Listen to it here.