The C-word

"I beg your pardon, Mister Ambassador?"
"I'm saying these cookies are simply delicious, Your Majesty."
The older staff members visibly paled.
"We," the Queen said gravely, "are not amused."
The younger amongst the staff exchanged puzzled looks, while the older members paled even more. Those words haven't been heard for more than two centuries. Until now.
"No colonial heathen shall utter the C-word within the premises of our residence! You have twenty-four hours to vacate your embassy, and all American military forces present within the United Kingdom have a week to withdraw."
The American ambassador just stared ahead, mouth agape.