Challenge! That might be your first instinct, thinking there's no way this is a word. But "za" is now accepted as slang for pizza and appears in the Official Tournament and Club Word List, the final authority for acceptable words in the U.S. and Canada. It's not much to look at, but "za" packs a big punch: With 10 points for the "z," it'll earn you least 11 total. Hit a triple letter square and you can score 31. Add pepperoni and you've got a meal.