Introduction:
Anytime during this scene, the players can be interrupted by the audience. If at anytime the audience doesn't like what the actors have said, they should make them change their sentence by yelling, 'should have said.'

Description:
Build a scene like any other. Give an extra pause between your comments to allow for the audience to interject. Listen closely for the audience's input. They will hear the 'should have said.' If you miss one, expect to be eaten alive. When you are expected to change what you said, make a strong choice that alters the course of the scene. They have yelled it because they don't like what is happening, so change the way the scene is going.

Gimmicks:
Replace long drawn out comments with short ones.

Variations:
The callers can be limited to one or two audience members if chaos is imminent.