Well, we have a real problem with the word "should", because people usually use should like "I am better than you, and therefore I say that you should ...." Legally speaking, there are no de jure Discordian "shoulds", but there are a lot of de facto ones.BTW, if you haven't read the Summa Discordia before, WAYSA? In my not so humble opinion, it is the second best Discordian text. Even then it is often better than the Principia Discordia because it doesn't use all of the mystical mumbo jumbo. You can find it on Geocities (until Geocities locks their front gate for good) or on good old Scribd.
As far as issues of morality are concerned, it's pretty wide open. One writer put it pretty well: "Goddess forbids nothing, but nobody likes an asshole." Being mean to weaker people isn't seen as very positive. Neither is going out of your way to mess with somebody who is minding their own business. You'll have a wider latitude when messing with an institution instead of an individual, but pointless destruction won't impress anyone.
You really should try to be creative, though, and funny too. If you finally wake up to the enormous, beautiful freedom of your existence and decide to spend it sitting passively in front of the tv, well, that's just sad. And you should have some courage, too - figure out what you think is the right thing to do, do it, and accept the consequences.
The most important thing is to realize that you are FREE! And, unless you feel like wasting it, freedom means becoming something, making choices, and taking responsibility for all the choices you make. If you are still spending your life just getting by, eating-and-excreting, then you don't quite Get It.
PS. If anyone has any info about the author(s) of the Summa Discordia please contact me. I haven't been able to find anything on this The Beatus Ffungo character.