The rules are simple: the top-level comments should all be in the form “The World’s Worst _____.” I’ll create a few to give you the idea.
Then you reply to other people’s top-level comments with your idea for the world’s worst … whatever. Let’s say world’s worst dentist. You can name a real person, or describe someone (real or not), or tell us what that person might say. Any way you can communicate what the world’s worst dentist might be like.
If you can’t picture what this means, this video might help: https://www.youtube.com/watch?v=AXCGTn8YS4o