This is my server jail, it changes the prisoners game mode to adventure so they can't even try to break the prison bars. All that you need to do is rig up a teleportation device that can transport the players to the prison. I would recommend [tp <player name> <x> <y> <z>] with the x y z being the coordinates of the cell which will vary depending on where you place it. I must ask you, if you are going to seriously jail someone please have a legitimate reason, you being a troll won't curb their behaviour. PLEASE comment below problems or praise and if you are feeling generous click the diamond. I will be happy to answer any queries that you have for me.