This is part of a (hopefully) recurring series explaining various “Internet memes”, which are catchphrases or concepts that take on a life of their own on the Internet. We’ll discuss sources, uses and I’ll give my own insight as to whether the meme deserved to even be.
It’s a English teacher’s worst nightmare. OK, maybe not as bad as trying to decipher Shaquille O’Neal’s Tweets, but still pretty bad.

The phrase showed up everywhere, even the desert
A few years back, the phrase “all your base are belong to us” took off across the Internet, then branched out into T-shirts and hacking pranks. Besides the horrible grammar, a lot of people were left wondering what the heck the point of this phrase was.
As it turns out, it was a standard case of a more-commonly occuring source of laughter: Engrish.
Engrish is the name given to poor translations of East Asian languages such as Japanese, Korean and various forms of Chinese into English, resulting often in English phrases that make very little or no sense whatsoever. There are numerous websites (such as this one) devoted to showing off the vast examples available of Engrish.

Here's a great example of Engrish. If you have any clue what this is talking about, congratulations.
One place Engrish showed up was in a video game called Zero Wing. Originally released in Japanese arcades in 1989, the game was released in home versions in both Japan and Europe for the Sega Mega Drive (better known here in the States as the Sega Genesis) in 1991.
Problem is, the European version was a little bit rushed, so some things were scrimped on, such as accurately translating the cut scene text from Japanese to English. And, as usual, that resulted in some Engrish.
The full Engrish of the cut scene can be found on Wikipedia. But, the important one to note is that what should have been “CATS (the name of the game’s antagonist) has taken all your bases” became “All your base are belong to us.”
Sometime in the late 90’s, the Engrished version was turned into a Flash video, which you can see here on YouTube. And, for whatever reason, “all your base belong to us” caught on. Here’s one possible explination, from a 2001 Wired article on the phrase:
I think there are a number of factors that combine to make All Your Base a fairly virulent meme. First, the incongruity of “engrish” in a reasonably nicely produced game is funny, much like professionally printed signs that happen to contain typos. Second … it works well as a catchphrase and slogan and fits easily into many different contexts. And, as any 12-year-old or online gamer knows, anything that was funny once is funnier when you repeat it 100 times.

And here it is. The source of it all.
My judgement: I can understand something in Engrish becoming a meme. Right or wrong, mocking aspects of foreign cultures we find quirky is a long-standing aspect of human life. But, why this particular one? I have no clue. It was a video game, and video game quirks tend to find favor on the Internet before other concepts. That’s about the best I can offer, because otherwise I can’t find anything that makes it otherwise deserving.