[sunilvarma]

Here's a way to do this. As this involves editing newthread.php, not everyone may like this solution.

Anyways, here's what to do:

(UPDATED) In newthread.php, FIND:

$newpost['iconid'] =& $vbulletin->GPC['iconid'];

REPLACE WITH:

if($vbulletin->GPC['iconid'] != 0){
		$newpost['iconid'] =& $vbulletin->GPC['iconid'];
	}
	else{		
		$icons_list = array();
		$iconids = $db->query_read("SELECT iconid FROM icon");
		while($row=mysql_fetch_assoc($iconids)){
			array_push($icons_list, $row);
		}
		$newpost['iconid'] = array_rand($icons_list) + 1;
	}

That should do it.

If you want to change the "No icon" text to "Random Icon" just edit the posticons template:

FIND:

$vbphrase[no_icon]

REPLACE WITH:

Random Icon

If anyone can implement this with a plugin, please show me how. And also let me know if the code is efficient.