_output called, but $output is empty

[eluser]Unknown[/eluser]
I have a method in my controller

Code:

function test() {
  print "test";
}

function _output($output) {
   var_dump($output);
}

_output() is being called, but $output is blank, and the output is sent, so that I see "test" first, then the var dump of an empty string.

I don't have caching on, no compression, no hooks, nothing I can see that would cause this. Any suggestions?

Thx,

Tac