Anonymuzs: Might I just say you are my new favourite person.
The "chans" have a lot of funny stuff that trickles down to the rest of the Internet.
A lot of people on the internet use a lot of jokes from the chan's. A large amount of Internet humour tends to be shock humour, black humour or ironic humour. This has nothing to do with Anonymous, just one of the facts of the Internet.
The thing about geek culture is it is so universally understood by other geeks that it seems like we all talk to each other constantly. You ask a geek in America what "All your base" is, and they know what you mean. You ask a geek in England or Australia or Canada and they will also understand. This doesn't mean we congregate, it just means that we have similar interests: Star Wars, Star Trek, Comics, Anime, Video Games, Computers, Myth Busters, Penn and Teller, Family Guy, South Park etc etc.
Most veteran Internet users tend to understand Internet culture well, and that's all Anonymous is. A bunch of veteran interest users, they don't all come from the Chan's, they don't all come from Something Awful, they don't all come Slashdot they don't all come from anywhere but they have all heard of these places. The reason we can organize in any way shape or form is because we all come from the same Internet culture.
You could almost replace "Anonymous" with "Veteran Internet User". Some Anonymous are good, some are bad, but the organization of Anonymous is actually a myth, and never really existed and doesn't really stand for anything. Its just a loose collection of Internet Users.
Even the list of "rules" people talk about, is ironic, its a parody - because Anonymous isn't an organization.
The whole thing is quite humourous really.