Alert Gate
This alert acts as a gate,
if the user doesn't click 'ok' they are bounced back to the previous page
Paste The
Following Code into the Body Section of Your Web Page 
<body
onload="CONFIRM">
<script
language="JavaScript">
function CONFIRM(){
if (!confirm ("This
alert acts as a gate, if the user doesn't click 'ok' they are bounced
back to the previous page!"))
history.go(-1);return " "
}
document.writeln(CONFIRM());
</script>