You probably are right. But that’s what was in the movies.
It was “Nuts”.
From what I have read McAuliffe was woken and told of the surrender demand. He said “aw nuts”. When ask what to tell the Germans he said that his first statement was good enough, to just tell them “nuts”.
The movie “Battle Ground” was a pretty damn good account of the Bastogne siege. Not the story of the Battle of the Bulge, but real good about Bastogne.