It's kind of like the F word, because you can use it however the hell you like. It can be a thing you do to someone; which can be a variety of things. Basically, whatever you decide to call a Sloppy Robert.
You can call someone Sloppy Robert, even if their name isn't Robert. Or variations such as Sloppy Bob, Slop Bob, or just Sloppy.
It has been considered, but not done yet, to create a sandwich and name it the Sloppy Robert.