Future In Laws is a cumbersome handle over layed on an open scene that has a predetermined concept. Typically the parents will speak the non-existent language. However the new partner could speak gibberish. This handle differs from typical translation scenes in that the translation is being done for another peroformer and the audience is observing.
Once the players are sitting on the couch one of them begins a repetitive activity. Encourage the players to contribute subtle motions combined with a quiet noise. Other players will mimic the activity and contribute their own repetitive actions to the group. The players create a fidgeting chorus line between themselves.