The rule If Don or Bruce leaves or throws belongings in my room, they are mine unless they want to pay 20¢ seemed a bit harsh, but I'm sure it was just Mike's way of saying "leave me the hell alone."
Simple crimes, like borrowing stuff without permission, calling names or socking someone only cost the perpetrator 5¢. More obscure offenses, like hanging around doorway, fooling with light switches, or Mike's legislative masterpiece, squealing when I want to look at something Don or Bruce has, shot up to 10¢.