crowding?

Does anyone know anything about room crowding in yahoo. Some guy came in a room that i had made and asked how i’d made it cos he wanted to crowd it, he seemed to think he was doing me a favour, but well we like our room of regulars and don’t want or need the room crowding with strangers. he said it would get us to the top of the room list and we’d stay there, but we don’t want to be there. However sometimes there are lots of people in a room and it does seem odd, when i mentioned a particular time to this guy he said yes he’d done it. How is he doing it, how can we stop him. he did seem nice enough but i’ve only seen him this once and so haven’t been able to ask him or stop him, like i said i think he really does think he’s helping.