The Private Rooms of the Stadium are rooms that are both normally empty and have no cameras. This allows them to be used for scheming and other activities in complete privacy (this is still a PG-13 story, don't get ideas).
Heather and Ezekiel's RoomEdit
Katie and Noah's RoomEdit
Noah and Katie, before the latter's elimination, used this room for the same reasons as Ezekiel and Heather. They were once barged in upon, to which Noah angrily and rhetorically questioned if the intruders wanted proof that he was straight.