Код
<div class="userhide">
[hide user="Admin"]Hidden Text[/hide]
[hide user="User"]Hidden Text From Another User[/hide]
[hide user="Admin"]Hidden Text 2[/hide]
[hide user="Admin"]Hidden Text 3[/hide]
[hide user="User"]Hidden Text From Another User[/hide]
</div>
Код
<script>
$(function(){
var username = '$USERNAME$';
$('.userhide').html($('.userhide').html().replace(/\[hide user="$USERNAME$"\](.*)\[\/hide\]/ig,"$1"));
$('.userhide').html($('.userhide').html().replace(/\[hide user="(.*)"\](.*)\[\/hide\]/ig,""));
});
</script>
