A high level player is caught in knightgf's steel cage.
A Steel cage is a trap that can be constructed in your throne room. It requires level 68 Construction to build, along with 5 mahogany planks and 20 steel bars. When it is activated by a lever, it simply comes down on the floorspace, trapping people that happen to stand on the floormat. The house owner can choose to release the prisoners. There is no possible way whatsoever to escape the steel cage without going to extreme measures. The steel cage is more preferred to 'annoy' people because they will get irritated after a while and demand to be let out.
Building a steel cage gives 1,100 Experience.