mmm "gumba" doesn't exist. Maybe you've hard about "cumpà" pronunced with a very long "a" like "cumpàààà". In this case it was meant to mean "compare" = mate/fellow (have a look here for some more meanings: http://it.wiktionary.org/wiki/compare) but the pronunciation of the word has been modified in the neapolitan dialect and it is now known as "cumpà". Nowadays young people can use "cumpa" (without an accent in the pronunciation of the A and also not emphasizing the lenght of it) to indicate their friends/team of friends - please notice that in this case we don't talk about "il cumpà" but about "la cumpa" "la mia cumpa" = all of my friends. "ué cumpà!" it's absolutely slang and used mainly in the south but we barely never use this phrase, it can happen once in a while joking or kidding.

I've only been in the north of Italy, and never heard this. Urbandictionary turned up a couple of definitions, but I've learnt not to trust that site. ;) Where did you find this?

I suppose you mean "gamba". Singular: gamba=leg Plural: gambe=legs

Sorry, I meant to write "Gumba" does exist, and "Some of us Call this...". THANKS

"Gumba does exist." Just not in proper Italian. In the United States, Italian-Americans of Neopolitan descent pronounce "compare" as "gumba." Likewise, "comare' is "goumada." I grew up in these communities, so figured I would chime in. Some of us all this the "lazy tongue." For instance, if you say Manicotti, I say Mah-nee-gawt (Manicott), where the "tt" becomes more of a d/th combination sound. All you have to go to hear Gumba is visit Italian sections of Boston, Philly, New York, etc.