What is the definition of Usmc0?

"Usmc0, my friend, is like the ultimate existential vacuum cleaner for naval vessels – it's so low on energy that it could power a small town, but it doesn't care if you're in the middle of a storm or trying to outrun a mermaid. Here's an edgy example: 'With usmc0, Captain Sink's ship is about to take a dip into the abyss of the sea, but he's convinced it'll just make him feel like he's the only person left who still thinks about existential dread.'"