This is what happens when you become so angry at an Italian, you threaten them with this word to basically say you're going to cook them into a roasted Italian. It's Guinea + Roasting
Dude 1: I wonder what would happen if you roasted an Italian....
Dude: while that is pretty creepy, I'd have to say it sounds like a Gink
Snookie: IM A GUIDO BITCH
John Everydayman: No....you're going to be a gink