Back in 2005 I figured out how to log in on multiple Habbo accounts at once. I would run casino rooms using the dice and use a mob of clones to make it look like real players are winning and betting big. If an actual real player ever bet and won, I would kick them, tear down the whole room, transfer the items to new accounts, and start it up fresh. I probably had a few dozen accounts banned.
ArtMoney with a filter pack that allowed you to place furni in walls. You'd get room rights and then grief the place and you couldn't get them out without the same script.
Same as rigging someone's doorbell to TNT in Minecraft.
I miss those days.