This script will act as a sort of barrier to prevent people from right clicking on your forum thus offering some sort of protection. There are ways to get round this but think of it as a hurdle which may put some people off.

Add the following code to the header template:
<script type="text/javascript">
<!--
var error="Right click functionality is disabled";

function clickIE4(){
if (event.button==2){
alert(message);
return false;
}
}

function clickNS4(e){
if (document.layers||document.getElementById&&!document.all){
if (e.which==2||e.which==3){
alert(message);
return false;
}
}
}

if (document.layers){
document.captureEvents(Event.MOUSEDOWN);
document.onmousedown=clickNS4;
}
else if (document.all&&!document.getElementById){
document.onmousedown=clickIE4;
}

document.oncontextmenu=new Function("alert(error);return false")

// -->
</script>

While this blocks the ability to Right Click, it also blocks the ability to copy and paste through the context menu that appears when Right Clicking. Copy and paste functionality is still available through the Ctrl+C and Ctrl+V shortcuts respectively.

Editing the Error Message:
Changing the message shown is a piece of cake. This can be done by finding this line near the top of the script:

var error="Right click functionality is disabled";

Change the text in quotes to anything you like.