Entire books have been written about baseball's unwritten rules — which somewhat defeats the purpose of “unwritten” — but they serve as good guides for fans who don’t know the ins and outs of the game. For example, who knew that it is considered poor gamesmanship to stand on the dirt near home plate while a pitcher is warming up? If you saw the highlights of last Sunday's Justin Verlander-Jered Weaver matchup, you have only scratched the surface. Scroll through this gallery for a look at baseball's most interesting rules that are allowed to be broken, but are frowned upon by many in the game and sometimes enforced by beanballs.