Yep, I have to deal with those all the time. Luckily, with girl's baseball, it's a little bit more relaxed but not always. Two seasons ago, I had stop one Dad from coaching his daughter (pitcher) from behind the cage. He was actually signaling pitch location.
If you want to see nutso parents, try hockey. The moms are the worst.
This is typical. Warning: NSFW language in video
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Clemens signed with the Jays because Toronto was the only team that would allow his kids on the field during warm-ups. He won two Cy Youngs, talked a lot about the great family environment, the great city, etc. and then bolted as soon as he got a better offer. He is much hated in this city.