var avatars = [
 'http://www.axiomfiles.com/Files/278466/avatar-Animal.jpg',
 'http://www.axiomfiles.com/Files/278466/avatar-bender.png',
 'http://www.axiomfiles.com/Files/278466/avatar-dalek.png',
 'http://www.axiomfiles.com/Files/278466/avatar-Gollum.jpg',
 'http://www.axiomfiles.com/Files/278466/avatar-hello-kitty2.png',
 'http://www.axiomfiles.com/Files/278466/avatar-snorlaxv.png'
];
// ***********************
// Don't change anything below
// ***********************
$('img[src*="empty-profile.png"]').each(function(){
 var rndm = Math.floor( Math.random() * (avatars.length) );
 $(this).attr('src', avatars[rndm]);
});
$('.gpWidget-officercontacts table.StyledList tbody tr').each(function(){
 var rndm = Math.floor( Math.random() * (avatars.length) );
 $(this).find('td:first:empty').html('<img align="left" style="height:32px;width:32px;border-width:0px;margin-right:3px;" src="' + avatars[rndm] + '">');
});

• Replace, or add more image urls (in orange) to pick from when replacing missing avatars.
• Make sure that all lines, but the last, ends with a comma.