OF ALL THE sapheaded excuses we have heard for expelling Christmas from a public school, the lamest came from right here in New Hampshire last week. At Hampton Academy Junior High, a seventh-grade student was refused entry to the holiday dance when he arrived in a Santa Claus costume. The reason? Allowing him in would be unconstitutional. Principal Fred Muscara was quoted in the Hampton Union as saying, "It was a holiday party. It was not a Christmas party. There is a separation of church and state. We have a lot of students that go to Hampton Academy Junior High...