[jQuery] $.getScript() - how to load into JSON formatted object?

[jquertil]

var blah = {
   something : function(variable){
      alert(variable);
   },
   something_else : 'hello'
}

alert( blah.something_else() ); // 'hello'
blah.something('whatsup'); // 'whatsup'

so far nothing unusual... but... how can I put the "blah.something"
function into a separate .js file and load it?
Played around with $.getScript() but nothing works :(
Ideally, my file "alert.js" would contain only the line with
"alert(variable);" in it. Can that be done?