nvm I got it
// Print the categories and forums
$result = $db->query('
SELECT c.id AS cid, c.cat_name, f.id AS fid,
f.forum_name, f.forum_desc, f.redirect_url,
f.moderators, f.num_topics, f.num_posts,
f.last_post, f.last_post_id, f.last_poster,
t.subject
FROM '.$db->prefix.'categories AS c
INNER JOIN '.$db->prefix.'forums AS f ON c.id=f.cat_id
INNER JOIN '.$db->prefix.'posts AS p ON p.id=f.last_post_id
INNER JOIN '.$db->prefix.'topics AS t ON t.id=p.topic_id
LEFT JOIN '.$db->prefix.'forum_perms AS fp ON (fp.forum_id=f.id AND fp.group_id='.$pun_user['g_id'].')
WHERE fp.read_forum IS NULL OR fp.read_forum=1
ORDER BY c.disp_position, c.id, f.disp_position
', true) or error('Unable to fetch category/forum list', __FILE__, __LINE__, $db->error());the part LEFT JOIN forum_perms did not have '.$db->prefix.' that up there does ^_^
