You need a script that sends a 500 something header. I can't remember what it is off the top of my head, but Javascript dies a flaming horrible death when you get an ajax response with this particular header type, which is how you get framebreaker code to keep from executing. The HUGE caveat is that no further JS will execute on the page. At All.
You mean 204 No Content? At least I have used that with frame breaker and it works but it cripples the browser nicely. Visitor can't exit from your page and do nothing than close it when he wants to leave
