Pagan spelling.
Burn the heretic.
Now that I've got your attention, I would like to ask users who are not American a couple of questions about American English spelling conventions.
How do you feel or what do you think when you see the American spelling of words such as colour, manoeuvre, aeon, and licence?
How do you feel or what do you think about some Americans using your spelling conventions, be they British or even Canadian ones?