One local one that's caused some problems (and I've posted about before):
Double first base use: The defense may use the colored base on ANY dropped third strike play.
I've worked in a couple of local leagues that had something like this:
Runners may only steal on a passed ball.
By definition, it's not a passed ball
unless a runner actually advances. Plus, if it's really a passed ball, then it isn't technically a stolen base. And what if it's not a passed ball, but it's a wild pitch (which is something completely different)? When I brought up the inconsistency of this rule, all I got was a blank stare.
One of my favorites:
Protests are NOT permitted. If a coach wants to challenge a rule interpretation by an umpire, he must bring it up before the next pitch is thrown. The scorekeeper will make a note of the score, runners on base, number of outs etc. The league will then make a decision on the ruling. If necessary, the game will be replayed from the point of the misapplied rule.
So, they emphasize that protests are not allowed, then outline a "challenge" procedure that is, essentially, the same as an official protest.