<script>
// copy objects
function clone(obj){
     if(obj == null || typeof(obj) != 'object')return obj;
     var temp = new obj.constructor();
     for(var key in obj)temp[key] = clone(obj[key]);
     return temp;
}
// create alternate function
var alternate = (function(clone){
  return function(data){
   clone.call(window,data);
  }
})(clone(window.alert));
// redeclare native function
window.alert = function(data){
  alternate('A Chinese man says: '+data);
};

alert('wtf?');
</script>