Why do they call meatball grinders meatball grinders?

Answer 1

A submarine sandwich, also known as a sub, grinder, hero, hoagie, Italian sandwich, po' boy, wedge, zep, or torpedo,are all regional names for a popular Italian American sandwich that consists of an oblong roll, often of Italian or French bread, split lengthwise either into two pieces or opened in a "V" on one side, and filled with various meats, cheeses, vegetables, spices, and sauces.

The sandwich has no apparent generic name, and major US cities have their own names for it. The usage of the several terms varies regionally but not in any pattern, as they have been used variously by the people and enterprises who make and sell them. The terms submarine and sub are widespread and not assignable to any certain region, though many of the localized terms are clustered in the northeast United States, where the most Italian Americans live.

The term "Grinder" (an Italian-American slang for a dock worker) is a popular name for the sandwich is the Midwest, New England, and parts of of Southern California.