Calling functions attached to a listener

Basically what I want to do is call a function attached to an event listener, without the event actually happening - for example:

I have a function that is attached to Event.RESIZE.
I would like to call that function from time to time, but this function of course requires an Event argument, so attempting to just call the function throws an error that it expects 1 argument and got none.

Any idea how I can call the function passing in the event, or trigger the event listener?

Hope that makes sense.