Each player has his own reason to change, and it affects each character differently. The caller should provide these changes at key points in the scene to provide for plot twists. Justification All members of team except one block, wimp, waffle , do bad mime, all forms of bad improv. Justification A scene begins. Players freeze, start a new TV show based on their positions.
Scene plays a bit, channel again changes.
Off stage players then change channels periodically between the three established shows. He does whatever the audience replies, then asks again. This works best if you show the audience that blocking or crass suggestions will get them nowhere. If you train the audience to do this, they will understand it's a skill. If the audience groans at a suggestion, go back and get a different suggestion.