Colocar pop-up de nao copiar

<script language=JavaScript>
<!--
var mensagem="Sua mensagem";
function clickIE() {if (document.all) {(mensagem);return false;}}
function clickNS(e) {if
(document.layers||(document.getElementById&&!document.all)) {
if (e.which==2||e.which==3) {(mensagem);return false;}}}
if (document.layers)
{document.captureEvents(Event.MOUSEDOWN);document.onmousedown=clickNS;}
else{document.onmouseup=clickNS;document.oncontextmenu=clickIE;}
document.oncontextmenu=new Function("return false")
// -->
</script>