Hundreds of thousands of people become US citizens every year. But only a few of them get naturalized on October 31st...and get to take the oath of citizenship in their Halloween costumes.
CORRECTION: This post originally said that children becoming US citizens have to pass the standard citizenship test. In fact, if a parent becomes a US citizen through the standard process (including a citizenship test), the child becomes eligible for citizenship without having to go through the full process. We apologize for the error.