it obviously was a "slow" time at JFK
the actual controller was right there, prompting the kid
the clearances made sense so the airline pilots didn't make a big deal about it (other false transmissions, like near Miami were obviously non standard clearances)
The FAA is so short handed on controllers that they shouldn't fire the controller or his boss. But they must promise to never do it again.
I can only imagine that things like this have happened before.
The FAA is guilty of many more sins than this incident.