You can call someone a meatball which would be like calling them a clown, fool, or someone wanting attention. It is the construction of "it up" that has most of us confused. Occasionally we say "it up" when indicating a way to be.
Some examples:
Live it up means you should enjoy your life more.
Ham it up means you should act like a ham\clown.
He was meatballing it up could mean he was acting like a meatball.