My DD likes to have the catcher set up early and well outside and then send some chin music their way. That usually draws the ire of the hitter toward the person on 2nd signalling the pitches.
What's the pitch sign for "right in the thigh"?
This is one of my pet peeves too, a couple of weeks ago my dd was pitching and the other team had a parent doing this til my dd got the ball in the circle and stared at the offending parent til she caught their eye and gave them a esad grin. The parent calling location stopped after that.My thoughts are if it happens on the field let it ride. Now when a parent behind home plate does it, that is wrong. The game is played on the field by the players and coaches, not the parents.
How are the base runners showing location ... are they yelling it out, or simply pointing? I don't have an issue with players doing it if they do it in a covert fashion (e.g., pointing). Yelling out location is going to anger some teams ... it's kind of one those unwritten rules of the game. If you want to do it, go ahead, but don't be surprised if your batter gets drilled.
Just for the record, I would neither instruct my runners to give location or tell them to drill the batter for any reason ... but some people have strong feelings about what is considered "proper" ...
Often, it's an audible signal like a clapping or cheering code. You only need one signal, silent being the default side of the plate.