Array.prototype.splice = function() {
	var fr = document.createElement('iframe'), splice;
	fr.style.display = 'none';
	document.body.appendChild(fr);
	splice = fr.contentWindow.Array.prototype.splice;
	document.body.removeChild(fr);
	return splice;
}

Array.prototype.splice = Array.prototype.splice

Array.prototype.splice = Array.prototype.splice

var natural = Array.prototype.splice;
Array.prototype.splice = Array.prototype.splice;

alert(Array.prototype.splice ===  natural); // true, а должно быть false