Passing Parameters To OnLoad In Aspx Page From Javascript?

I have this javascript

function myFunction(source) {
window.open(source, "Title", 'width=400, height=400');
}

and in c# code I call it by

HtmlPage.Window.Invoke("myFunction", source);

which opens up a aspx page and goes to its OnLoad function:

protected override void OnLoad(System.EventArgs e)
{
base.OnLoad(e);

how do I pass in parameters to the event args in the aspx page? or is that even possible? and how can I pass these parameters from my c# code to the javascript?