Hello. I'm recently in "no more volcano" and "Random minecraft server" and I saw a very strange thing. One guy was floating in the air and in one moment filled half of the map with sand, the server was lagging so messages were received after 30 seconds. He got banned. Next was another guy who filled second half of the map with gravel. Next was the guy who sunblocked almost entire map. All in one day. Server looks now like a piece of s**t. What to do? Did you see that on your servers?
EDIT: That's a link to saved level of that moment. EDIT2: Doesn't work anyway.