I just rolled with those moments and often they resolved themselves if I kept my cool or even joined in.

One example was a kid that was outright breakdancing before the first bell right in the middle of the classroom.

I (truthfully) acknowledged he was amazing but that he had til the second bell to clear out. He spun on his head and shoulder like a top and the first kids to come in had a good time watching before they started sliding desks into place.