Extra Username Validation

Run a family-friendly site and want to make sure no inappropriate words end up in usernames? Use this

add_filter( 'validate_username', 'forbidden_username_terms', 10, 2);
function forbidden_username_terms($valid, $username) {
	$badwords = array('badword','nogood');
	foreach($badwords as $bw) {
		if (strpos($username,$bw) !== false) return false; 
	}
	return $username;
}