As in spaghetti and meatballs. To prepare the meatballs, chopped or ground
meat must first be somewhat deep-fried before it is added to a tomato sauce, where it is allowed to simmer in the sauce for a while before serving.
Hence the meatball being a "greaseball."
Although meatballs are and have been for centuries, a widely used
food preparation for
meat among many races all over the world, it is by no means only an Italian
food preparation.
To another culture's
food that
may be more on the bland or less spicy side, and less complicated in preparation, as in steamed, boiled, broiled or
raw, the combination of a fried
meat added to a spicy tomato sauce that also includes
oil, as in olive oil, in its preparation, Italian meatballs would stand out as particularly greasy or oily, to where any perceived ethnic differences would be seen as linked with the choice of
food as a "you are what you eat" concept. And that eating complicated and hard to digest foods or "greasy" foods in this case, would have an assumed negative or peculiar affect on a person's mental abilities, outlook, as well as physical attributes, oily skin, greasy hair, to where a racial slur would be invented on the basis of presumed ethnic characteristics stemming from particular
food type consumption alone.