Basically I lurked (swinging about once a month maybe) since about...2009? I think? And only started posting and stuff this year. I still have some questions regarding certain things on the codex and search has failed me (which is what it seems to do 99% of the time). Since Socrates was all cool and stuff and said that you should start by admitting that you know nothing, anybody willing to enlighten a mind seeking knowledge?
: I get its used for "I am watching you" sort of posts but I have no idea who this pizza guy is.
It's from a picture of a guy in a movie theater with 3D glasses eating pizza with no fucks given. That's it. There's no greater meaning and people use it in a variety of ways, but it mostly seems to connotate the most Kwa of consumer stereotypes.
: Freud from Ultima, I guess its used for psycho-analysis puns?
Nah, you're way off on this one. Basically there are some pretty disturbed posters on the Codex, and one of them had fucking actual text files of writeups on people based on stuff they had admitted on the Codex. Other people thought this was hilarious and turned it into a meme. Like most of these in-jokes, no one using them is actually serious.
Prosperland: The site redirect in case of extreme stupidity, based on a "interesting" poster?
Prosper is a very special individual, but I know less about him than some people, so I'll leave his sordid ways to someone else to describe in detail, but the best description I can give of him is imagine a "developer" like Cleve, if Cleve were 10X more shut-in, smeared feces on his own walls, and had never actually finished anything. He has made some pretty wondrous works of art, though. Just don't ask him about his "AI".
The psychic harm caused (in others) by exposing him to all and sundry was too great, so he was segregated into his own forum for the good of all. Picture a deranged illithid mindraping everyone on accident and you've got a good analogy for why this happened. People are treated to being trapped in this forum as a punishment because it is far more dire a fate than any simple ban could ever be. The same principle (a punishment worse than death) is behind redirecting people to RPGWatch.
Kingcomrade: The poster RPG codex deserves but not the one it needs. I know about this sordid tale, it is just funny to mention.
Believe it or not, Kingcomrade was actually a pretty funny poster once upon a time. I guess like most people he went down-hill after too long exposure to GD.
Kwa/Kwan: I get its used to represent the United States of America but where does it come from?
This one is a little complicated. It's a racial description of the United States, rooted in Kwanzaa. i.e, the implication is that the United States is now some sort of failed third world -stan, with the added emphasis that it is being taken over by congoid rape gangs. Like a lot of later in-jokes, this one owes its popularity to the Codex's "embrace" of Cleveland Blakemore. It's really no more than copypasta of one of Cleve's blog posts.
: Why is Mr. Ziets depicted as a goth/emo? He looks dorky if anything.
Because someone thought he looked silly and decided to photoshop the original "you don't say" face emoticon. No greater meaning here.
: I take it is based on that fantasy is running around killing things on horses quote?
I don't remember the specifics, but it's from a Dragon Age: Inquisition preorder bonus. Gaider is a hated Bioware employee, he's gay, they added black unicorns you can ride as a selling point, this joke writes itself.
: Did the term originate from RPG Codex?
I'm actually pretty sure this reference predates Codex or might have spread beyond its walls, but it is certainly not one you're likely to find referred to outside the Codex much. If you do, it's probably an escapee from the Codex. Cover shooters have been criticized for being like a circus carnival game of whack-a-mole, but the condensed single word usage of "popamole" is definitely a Codex special, especially when applied to things that aren't strictly shooters.
Hope this helps, faggot.