"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.