squibs with lines of dialogue, quotes, phrases, etc. Also location, setting, characters, etc., as necessary
The squibs will serve as dialogue for the scene. Given a scenario, the actors must perform the scene, randomly picking up the squibs and using whatever is written on them as their next line of dialogue. For example, in a scene about three men trying to fit a horse into a suitcase, one might pick up a squib with the quote, "When in doubt, stand and pout." It is, of course, nonsensical and not fitting with the scene, but the actor must fit it in, perhaps suggesting that if all three actors stand and pout, the horse will feel guilty and get into the suitcase by himself.
When asking for the audience's input, it helps to limit them to quotes from movies and television, or popular sayings and phrases. This will ensure that complete sentences are provided and usable. Also, have an individual not participating in the game screen all the squibs not only for appropriateness but humor. The squib need not be funny in itself, rather it should be odd enough to generate sufficient comedy in the scene.