What would you have said, instead of "Et tu, Brute?"?

In Shakespeare’s famous Julius Caesar, he is attacked and killed by a group of senators, including his friend Brutus (Brute). Among his last words were the famous “Et tu, Brute?”, which translates to “And you, Brutus?”

If you were being attacked and noticed that even your good friend was participating, how would you acknowledge that? What would you say to that friend?