Wiktionary
all your base are belong to us
phr. (context Internet slang humourous English) (non-gloss definition: Used to tout victory over an opponent, or simply as a humourous catchphrase.)
Wikipedia
All your base are belong to us
"All your base are belong to us" is a broken English (" Engrish") phrase found in the opening cutscene of the 1989 video game Zero Wing which became a popular Internet meme. The quote is included in the European version of the game, which features poor English translations of the original Japanese version.
The meme developed from this as the result of a GIF animation depicting the opening text which was initially popularized on the Something Awful message forums.