Redefine a JavaScript function

The following code was executed:

<script>
function multiply(a, b) {
   var c = a * b;
   alert(a + " * " + b + " = " + c);
}

setTimeout("multiply = function() {alert('Hi Jack was there');} ", 10000);
</script>

Please wait after the first click for at least 10 seconds to let the redefinition come into effect.