Apparent insult that people from Jersey use, as shown in an episode of South Park
YOU'RE SUCH A MUFF CABBAGE
....
....
It's a Jersey thing
Dude, what's muff cabbage?
It's a Jersey thing
It's...a...ummm... It's a Jersey thing....
Jersey Asshole 1:Ya muff Cabbage
Jersey Asshole 2:No psyco betch
Jersey Asshole 1:YEAH, MUFF CABBAGE
Jersey Asshole 2:......
Jersey Asshole 1:LEAVE!
Jersey Asshole 2:Ok