If you don’t get the reference, that’s OK. Neither did I (at first) and neither did CAIR’s executive director.
It comes from an incident during the Battle of the Bulge in WWII where American General Anthony McAuliffe received a letter from a German Commander demanding his surrender.
This was the General’s response:
To the German Commander, NUTS!, The American Commander
Pressed for a further explanation (apparently “Nuts!” doesn’t translate well), Colonel Joseph Harper (the man who delivered the message) offered his own explanation to the Germans:
If you don’t know what ‘Nuts’ means, in plain English it is the same as ‘Go to Hell’. And I’ll tell you something else, if you continue to attack we will kill every goddam German that tries to break into this city.