Yes. When you get two or more kids together they hype each other up. So if one yells another yells louder. If one squeals they all squeal. If one runs they all run.
It's a pack thing.
The only way to calm them down is to use a very serious and deep voice, and tell them they are breaking the rules, they need to use a quiet "indoor voice", and, (big whammy here) if they don't you will separate them.
That's serious business right there.
Putting on a movie also helps. They'll "shush" each other trying to hear it. (Keep the volume low).
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