Fighting in jail
Introduce the feature where you can challenge or simply attack someone in jail. Also a way of training in jail could be added. Even if it means spending more time in jail, at least it would make it a little more similar to a real jail and could. That would bring some extra action when you go to jail. After all thats basically what inmates do anyway.
this is ridiculous idea :) training in jail - yes. fighting in jail? - no.